* [PATCH 0/12] Per-bdi writeback flusher threads #5
@ 2009-05-25 7:34 Jens Axboe
2009-05-25 7:34 ` [PATCH 01/12] ntfs: remove old debug check for dirty data in ntfs_put_super() Jens Axboe
` (11 more replies)
0 siblings, 12 replies; 27+ messages in thread
From: Jens Axboe @ 2009-05-25 7:34 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, hch, akpm, jack, yanmin_zhang
Hi,
Here's the 6th version of the writeback patches, it's identical to v5
that got garbled on posting.
- Missing memory barrier before wake_up_bit() could cause weird stalls,
now fixed.
- Use dynamic bdi_work allocation in bdi_start_writeback(). We still
fall back to the stack allocation if this should fail. But with the
dynamic we don't have to wait for wb threads to have noticed the work,
so the dynamic allocaiton avoids that (small) serialization point.
- Pass down wbc->sync_mode so queued work doesn't always use
WB_SYNC_NONE in __wb_writeback() (Thanks Jan Kara).
- Don't check background threshold for WB_SYNC_ALL in __wb_writeback.
This would sometimes leave dirty data around when the system became
idle.
- Make bdi_writeback_all() and the write path from
generic_sync_sb_inodes() write out in-line instead of punting to the
wb threads. This retains the behaviour we have in the kernel now and
also fixes the oops reported by Yanmin Zhang.
- Replace rcu/spin_lock_bh protected bdi_list and bdi_pending_list with
a simple mutex. This both simplied the code (and allowed for the above
fix easily) and made the locking there more trivial. This doesn't
hurt the fast path, since that path is generally only done for full
system sync.
- Let bdi_forker_task() wake up at dirty_writeback_interval like the wb
threads, so that potential dirty data on the default_backing_dev_info
gets flushed at the same intervals.
- When bdi_forker_task() wakes up, let it scan the bdi_list for bdi's
with dirty data. If it finds one and it doesn't have an associated
writeback thread, start one. Otherwise we could have to reach memory
pressure conditions before some threads got started, meaning that
dirty data for those almost idle devices sat around for a long time.
- Call try_to_freeze() in bdi_forker_task(). It's defined as freezable,
so if we don't freeze then we get hangs on suspend.
- Pull out the ntfs sb_has_dirty_io() part and add it at the front as a
preparatory patch. Ditto the btrfs bdi register patch.
- Shuffle some patches around for a cleaner series. Made sure it's all
bisectable.
I ran performance testing again and compared to v4, and as expected it's
the same. The changes are mostly in the sync(1) or umount writeback
paths, so the general writeback functions like in v4.
This should be pretty much final and mergeable. So please run your
favorite performance benchmarks that exercise buffered writeout and
report any problems and/or performance differences (good as well as bad,
please). Thanks!
--
Jens Axboe
^ permalink raw reply [flat|nested] 27+ messages in thread
* [PATCH 01/12] ntfs: remove old debug check for dirty data in ntfs_put_super()
2009-05-25 7:34 [PATCH 0/12] Per-bdi writeback flusher threads #5 Jens Axboe
@ 2009-05-25 7:34 ` Jens Axboe
2009-05-25 7:34 ` [PATCH 02/12] btrfs: properly register fs backing device Jens Axboe
` (10 subsequent siblings)
11 siblings, 0 replies; 27+ messages in thread
From: Jens Axboe @ 2009-05-25 7:34 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, hch, akpm, jack, yanmin_zhang, Jens Axboe
This should not trigger anymore, so kill it.
Acked-by: Anton Altaparmakov <aia21@cam.ac.uk>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
fs/ntfs/super.c | 33 +++------------------------------
1 files changed, 3 insertions(+), 30 deletions(-)
diff --git a/fs/ntfs/super.c b/fs/ntfs/super.c
index f76951d..3fc03bd 100644
--- a/fs/ntfs/super.c
+++ b/fs/ntfs/super.c
@@ -2373,39 +2373,12 @@ static void ntfs_put_super(struct super_block *sb)
vol->mftmirr_ino = NULL;
}
/*
- * If any dirty inodes are left, throw away all mft data page cache
- * pages to allow a clean umount. This should never happen any more
- * due to mft.c::ntfs_mft_writepage() cleaning all the dirty pages as
- * the underlying mft records are written out and cleaned. If it does,
- * happen anyway, we want to know...
+ * We should have no dirty inodes left, due to
+ * mft.c::ntfs_mft_writepage() cleaning all the dirty pages as
+ * the underlying mft records are written out and cleaned.
*/
ntfs_commit_inode(vol->mft_ino);
write_inode_now(vol->mft_ino, 1);
- if (sb_has_dirty_inodes(sb)) {
- const char *s1, *s2;
-
- mutex_lock(&vol->mft_ino->i_mutex);
- truncate_inode_pages(vol->mft_ino->i_mapping, 0);
- mutex_unlock(&vol->mft_ino->i_mutex);
- write_inode_now(vol->mft_ino, 1);
- if (sb_has_dirty_inodes(sb)) {
- static const char *_s1 = "inodes";
- static const char *_s2 = "";
- s1 = _s1;
- s2 = _s2;
- } else {
- static const char *_s1 = "mft pages";
- static const char *_s2 = "They have been thrown "
- "away. ";
- s1 = _s1;
- s2 = _s2;
- }
- ntfs_error(sb, "Dirty %s found at umount time. %sYou should "
- "run chkdsk. Please email "
- "linux-ntfs-dev@lists.sourceforge.net and say "
- "that you saw this message. Thank you.", s1,
- s2);
- }
#endif /* NTFS_RW */
iput(vol->mft_ino);
--
1.6.3.rc0.1.gf800
^ permalink raw reply related [flat|nested] 27+ messages in thread
* [PATCH 02/12] btrfs: properly register fs backing device
2009-05-25 7:34 [PATCH 0/12] Per-bdi writeback flusher threads #5 Jens Axboe
2009-05-25 7:34 ` [PATCH 01/12] ntfs: remove old debug check for dirty data in ntfs_put_super() Jens Axboe
@ 2009-05-25 7:34 ` Jens Axboe
2009-05-25 7:34 ` [PATCH 03/12] writeback: move dirty inodes from super_block to backing_dev_info Jens Axboe
` (9 subsequent siblings)
11 siblings, 0 replies; 27+ messages in thread
From: Jens Axboe @ 2009-05-25 7:34 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, hch, akpm, jack, yanmin_zhang, Jens Axboe
btrfs assigns this bdi to all inodes on that file system, so make
sure it's registered. This isn't really important now, but will be
when we put dirty inodes there. Even now, we miss the stats when the
bdi isn't visible.
Also fixes failure to check bdi_init() return value, and bad inherit of
->capabilities flags from the default bdi.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
fs/btrfs/disk-io.c | 23 ++++++++++++++++++-----
1 files changed, 18 insertions(+), 5 deletions(-)
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 4b0ea0b..2dc19c9 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1345,12 +1345,24 @@ static void btrfs_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
free_extent_map(em);
}
+/*
+ * If this fails, caller must call bdi_destroy() to get rid of the
+ * bdi again.
+ */
static int setup_bdi(struct btrfs_fs_info *info, struct backing_dev_info *bdi)
{
- bdi_init(bdi);
+ int err;
+
+ bdi->capabilities = BDI_CAP_MAP_COPY;
+ err = bdi_init(bdi);
+ if (err)
+ return err;
+
+ err = bdi_register(bdi, NULL, "btrfs");
+ if (err)
+ return err;
+
bdi->ra_pages = default_backing_dev_info.ra_pages;
- bdi->state = 0;
- bdi->capabilities = default_backing_dev_info.capabilities;
bdi->unplug_io_fn = btrfs_unplug_io_fn;
bdi->unplug_io_data = info;
bdi->congested_fn = btrfs_congested_fn;
@@ -1574,7 +1586,8 @@ struct btrfs_root *open_ctree(struct super_block *sb,
fs_info->sb = sb;
fs_info->max_extent = (u64)-1;
fs_info->max_inline = 8192 * 1024;
- setup_bdi(fs_info, &fs_info->bdi);
+ if (setup_bdi(fs_info, &fs_info->bdi))
+ goto fail_bdi;
fs_info->btree_inode = new_inode(sb);
fs_info->btree_inode->i_ino = 1;
fs_info->btree_inode->i_nlink = 1;
@@ -1931,8 +1944,8 @@ fail_iput:
btrfs_close_devices(fs_info->fs_devices);
btrfs_mapping_tree_free(&fs_info->mapping_tree);
+fail_bdi:
bdi_destroy(&fs_info->bdi);
-
fail:
kfree(extent_root);
kfree(tree_root);
--
1.6.3.rc0.1.gf800
^ permalink raw reply related [flat|nested] 27+ messages in thread
* [PATCH 03/12] writeback: move dirty inodes from super_block to backing_dev_info
2009-05-25 7:34 [PATCH 0/12] Per-bdi writeback flusher threads #5 Jens Axboe
2009-05-25 7:34 ` [PATCH 01/12] ntfs: remove old debug check for dirty data in ntfs_put_super() Jens Axboe
2009-05-25 7:34 ` [PATCH 02/12] btrfs: properly register fs backing device Jens Axboe
@ 2009-05-25 7:34 ` Jens Axboe
2009-05-25 8:42 ` Jan Kara
2009-05-25 7:34 ` [PATCH 04/12] writeback: switch to per-bdi threads for flushing data Jens Axboe
` (8 subsequent siblings)
11 siblings, 1 reply; 27+ messages in thread
From: Jens Axboe @ 2009-05-25 7:34 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, hch, akpm, jack, yanmin_zhang, Jens Axboe
This is a first step at introducing per-bdi flusher threads. We should
have no change in behaviour, although sb_has_dirty_inodes() is now
ridiculously expensive, as there's no easy way to answer that question.
Not a huge problem, since it'll be deleted in subsequent patches.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
fs/fs-writeback.c | 196 +++++++++++++++++++++++++++---------------
fs/super.c | 3 -
include/linux/backing-dev.h | 9 ++
include/linux/fs.h | 5 +-
mm/backing-dev.c | 30 +++++++
mm/page-writeback.c | 11 +--
6 files changed, 170 insertions(+), 84 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 91013ff..1137408 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -25,6 +25,7 @@
#include <linux/buffer_head.h>
#include "internal.h"
+#define inode_to_bdi(inode) ((inode)->i_mapping->backing_dev_info)
/**
* writeback_acquire - attempt to get exclusive writeback access to a device
@@ -158,12 +159,13 @@ void __mark_inode_dirty(struct inode *inode, int flags)
goto out;
/*
- * If the inode was already on s_dirty/s_io/s_more_io, don't
- * reposition it (that would break s_dirty time-ordering).
+ * If the inode was already on b_dirty/b_io/b_more_io, don't
+ * reposition it (that would break b_dirty time-ordering).
*/
if (!was_dirty) {
inode->dirtied_when = jiffies;
- list_move(&inode->i_list, &sb->s_dirty);
+ list_move(&inode->i_list,
+ &inode_to_bdi(inode)->b_dirty);
}
}
out:
@@ -184,31 +186,30 @@ static int write_inode(struct inode *inode, int sync)
* furthest end of its superblock's dirty-inode list.
*
* Before stamping the inode's ->dirtied_when, we check to see whether it is
- * already the most-recently-dirtied inode on the s_dirty list. If that is
+ * already the most-recently-dirtied inode on the b_dirty list. If that is
* the case then the inode must have been redirtied while it was being written
* out and we don't reset its dirtied_when.
*/
static void redirty_tail(struct inode *inode)
{
- struct super_block *sb = inode->i_sb;
+ struct backing_dev_info *bdi = inode_to_bdi(inode);
- if (!list_empty(&sb->s_dirty)) {
- struct inode *tail_inode;
+ if (!list_empty(&bdi->b_dirty)) {
+ struct inode *tail;
- tail_inode = list_entry(sb->s_dirty.next, struct inode, i_list);
- if (time_before(inode->dirtied_when,
- tail_inode->dirtied_when))
+ tail = list_entry(bdi->b_dirty.next, struct inode, i_list);
+ if (time_before(inode->dirtied_when, tail->dirtied_when))
inode->dirtied_when = jiffies;
}
- list_move(&inode->i_list, &sb->s_dirty);
+ list_move(&inode->i_list, &bdi->b_dirty);
}
/*
- * requeue inode for re-scanning after sb->s_io list is exhausted.
+ * requeue inode for re-scanning after bdi->b_io list is exhausted.
*/
static void requeue_io(struct inode *inode)
{
- list_move(&inode->i_list, &inode->i_sb->s_more_io);
+ list_move(&inode->i_list, &inode_to_bdi(inode)->b_more_io);
}
static void inode_sync_complete(struct inode *inode)
@@ -255,18 +256,50 @@ static void move_expired_inodes(struct list_head *delaying_queue,
/*
* Queue all expired dirty inodes for io, eldest first.
*/
-static void queue_io(struct super_block *sb,
- unsigned long *older_than_this)
+static void queue_io(struct backing_dev_info *bdi,
+ unsigned long *older_than_this)
+{
+ list_splice_init(&bdi->b_more_io, bdi->b_io.prev);
+ move_expired_inodes(&bdi->b_dirty, &bdi->b_io, older_than_this);
+}
+
+static int sb_on_inode_list(struct super_block *sb, struct list_head *list)
{
- list_splice_init(&sb->s_more_io, sb->s_io.prev);
- move_expired_inodes(&sb->s_dirty, &sb->s_io, older_than_this);
+ struct inode *inode;
+ int ret = 0;
+
+ spin_lock(&inode_lock);
+ list_for_each_entry(inode, list, i_list) {
+ if (inode->i_sb == sb) {
+ ret = 1;
+ break;
+ }
+ }
+ spin_unlock(&inode_lock);
+ return ret;
}
int sb_has_dirty_inodes(struct super_block *sb)
{
- return !list_empty(&sb->s_dirty) ||
- !list_empty(&sb->s_io) ||
- !list_empty(&sb->s_more_io);
+ struct backing_dev_info *bdi;
+ int ret = 0;
+
+ /*
+ * This is REALLY expensive right now, but it'll go away
+ * when the bdi writeback is introduced
+ */
+ mutex_lock(&bdi_lock);
+ list_for_each_entry(bdi, &bdi_list, bdi_list) {
+ if (sb_on_inode_list(sb, &bdi->b_dirty) ||
+ sb_on_inode_list(sb, &bdi->b_io) ||
+ sb_on_inode_list(sb, &bdi->b_more_io)) {
+ ret = 1;
+ break;
+ }
+ }
+ mutex_unlock(&bdi_lock);
+
+ return ret;
}
EXPORT_SYMBOL(sb_has_dirty_inodes);
@@ -322,11 +355,11 @@ __sync_single_inode(struct inode *inode, struct writeback_control *wbc)
/*
* We didn't write back all the pages. nfs_writepages()
* sometimes bales out without doing anything. Redirty
- * the inode; Move it from s_io onto s_more_io/s_dirty.
+ * the inode; Move it from b_io onto b_more_io/b_dirty.
*/
/*
* akpm: if the caller was the kupdate function we put
- * this inode at the head of s_dirty so it gets first
+ * this inode at the head of b_dirty so it gets first
* consideration. Otherwise, move it to the tail, for
* the reasons described there. I'm not really sure
* how much sense this makes. Presumably I had a good
@@ -336,7 +369,7 @@ __sync_single_inode(struct inode *inode, struct writeback_control *wbc)
if (wbc->for_kupdate) {
/*
* For the kupdate function we move the inode
- * to s_more_io so it will get more writeout as
+ * to b_more_io so it will get more writeout as
* soon as the queue becomes uncongested.
*/
inode->i_state |= I_DIRTY_PAGES;
@@ -402,10 +435,10 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
if ((wbc->sync_mode != WB_SYNC_ALL) && (inode->i_state & I_SYNC)) {
/*
* We're skipping this inode because it's locked, and we're not
- * doing writeback-for-data-integrity. Move it to s_more_io so
- * that writeback can proceed with the other inodes on s_io.
+ * doing writeback-for-data-integrity. Move it to b_more_io so
+ * that writeback can proceed with the other inodes on b_io.
* We'll have another go at writing back this inode when we
- * completed a full scan of s_io.
+ * completed a full scan of b_io.
*/
requeue_io(inode);
return 0;
@@ -428,51 +461,34 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
return __sync_single_inode(inode, wbc);
}
-/*
- * Write out a superblock's list of dirty inodes. A wait will be performed
- * upon no inodes, all inodes or the final one, depending upon sync_mode.
- *
- * If older_than_this is non-NULL, then only write out inodes which
- * had their first dirtying at a time earlier than *older_than_this.
- *
- * If we're a pdflush thread, then implement pdflush collision avoidance
- * against the entire list.
- *
- * If `bdi' is non-zero then we're being asked to writeback a specific queue.
- * This function assumes that the blockdev superblock's inodes are backed by
- * a variety of queues, so all inodes are searched. For other superblocks,
- * assume that all inodes are backed by the same queue.
- *
- * FIXME: this linear search could get expensive with many fileystems. But
- * how to fix? We need to go from an address_space to all inodes which share
- * a queue with that address_space. (Easy: have a global "dirty superblocks"
- * list).
- *
- * The inodes to be written are parked on sb->s_io. They are moved back onto
- * sb->s_dirty as they are selected for writing. This way, none can be missed
- * on the writer throttling path, and we get decent balancing between many
- * throttled threads: we don't want them all piling up on inode_sync_wait.
- */
-void generic_sync_sb_inodes(struct super_block *sb,
- struct writeback_control *wbc)
+static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
+ struct writeback_control *wbc,
+ struct super_block *sb,
+ int is_blkdev_sb)
{
const unsigned long start = jiffies; /* livelock avoidance */
- int sync = wbc->sync_mode == WB_SYNC_ALL;
spin_lock(&inode_lock);
- if (!wbc->for_kupdate || list_empty(&sb->s_io))
- queue_io(sb, wbc->older_than_this);
- while (!list_empty(&sb->s_io)) {
- struct inode *inode = list_entry(sb->s_io.prev,
+ if (!wbc->for_kupdate || list_empty(&bdi->b_io))
+ queue_io(bdi, wbc->older_than_this);
+
+ while (!list_empty(&bdi->b_io)) {
+ struct inode *inode = list_entry(bdi->b_io.prev,
struct inode, i_list);
- struct address_space *mapping = inode->i_mapping;
- struct backing_dev_info *bdi = mapping->backing_dev_info;
long pages_skipped;
+ /*
+ * super block given and doesn't match, skip this inode
+ */
+ if (sb && sb != inode->i_sb) {
+ redirty_tail(inode);
+ continue;
+ }
+
if (!bdi_cap_writeback_dirty(bdi)) {
redirty_tail(inode);
- if (sb_is_blkdev_sb(sb)) {
+ if (is_blkdev_sb) {
/*
* Dirty memory-backed blockdev: the ramdisk
* driver does this. Skip just this inode
@@ -494,14 +510,14 @@ void generic_sync_sb_inodes(struct super_block *sb,
if (wbc->nonblocking && bdi_write_congested(bdi)) {
wbc->encountered_congestion = 1;
- if (!sb_is_blkdev_sb(sb))
+ if (!is_blkdev_sb)
break; /* Skip a congested fs */
requeue_io(inode);
continue; /* Skip a congested blockdev */
}
if (wbc->bdi && bdi != wbc->bdi) {
- if (!sb_is_blkdev_sb(sb))
+ if (!is_blkdev_sb)
break; /* fs has the wrong queue */
requeue_io(inode);
continue; /* blockdev has wrong queue */
@@ -539,13 +555,55 @@ void generic_sync_sb_inodes(struct super_block *sb,
wbc->more_io = 1;
break;
}
- if (!list_empty(&sb->s_more_io))
+ if (!list_empty(&bdi->b_more_io))
wbc->more_io = 1;
}
- if (sync) {
+ spin_unlock(&inode_lock);
+ /* Leave any unwritten inodes on b_io */
+}
+
+/*
+ * Write out a superblock's list of dirty inodes. A wait will be performed
+ * upon no inodes, all inodes or the final one, depending upon sync_mode.
+ *
+ * If older_than_this is non-NULL, then only write out inodes which
+ * had their first dirtying at a time earlier than *older_than_this.
+ *
+ * If we're a pdlfush thread, then implement pdflush collision avoidance
+ * against the entire list.
+ *
+ * If `bdi' is non-zero then we're being asked to writeback a specific queue.
+ * This function assumes that the blockdev superblock's inodes are backed by
+ * a variety of queues, so all inodes are searched. For other superblocks,
+ * assume that all inodes are backed by the same queue.
+ *
+ * FIXME: this linear search could get expensive with many fileystems. But
+ * how to fix? We need to go from an address_space to all inodes which share
+ * a queue with that address_space. (Easy: have a global "dirty superblocks"
+ * list).
+ *
+ * The inodes to be written are parked on bdi->b_io. They are moved back onto
+ * bdi->b_dirty as they are selected for writing. This way, none can be missed
+ * on the writer throttling path, and we get decent balancing between many
+ * throttled threads: we don't want them all piling up on inode_sync_wait.
+ */
+void generic_sync_sb_inodes(struct super_block *sb,
+ struct writeback_control *wbc)
+{
+ const int is_blkdev_sb = sb_is_blkdev_sb(sb);
+ struct backing_dev_info *bdi;
+
+ mutex_lock(&bdi_lock);
+ list_for_each_entry(bdi, &bdi_list, bdi_list)
+ generic_sync_bdi_inodes(bdi, wbc, sb, is_blkdev_sb);
+ mutex_unlock(&bdi_lock);
+
+ if (wbc->sync_mode == WB_SYNC_ALL) {
struct inode *inode, *old_inode = NULL;
+ spin_lock(&inode_lock);
+
/*
* Data integrity sync. Must wait for all pages under writeback,
* because there may have been pages dirtied before our sync
@@ -583,10 +641,8 @@ void generic_sync_sb_inodes(struct super_block *sb,
}
spin_unlock(&inode_lock);
iput(old_inode);
- } else
- spin_unlock(&inode_lock);
+ }
- return; /* Leave any unwritten inodes on s_io */
}
EXPORT_SYMBOL_GPL(generic_sync_sb_inodes);
@@ -601,8 +657,8 @@ static void sync_sb_inodes(struct super_block *sb,
*
* Note:
* We don't need to grab a reference to superblock here. If it has non-empty
- * ->s_dirty it's hadn't been killed yet and kill_super() won't proceed
- * past sync_inodes_sb() until the ->s_dirty/s_io/s_more_io lists are all
+ * ->b_dirty it's hadn't been killed yet and kill_super() won't proceed
+ * past sync_inodes_sb() until the ->b_dirty/b_io/b_more_io lists are all
* empty. Since __sync_single_inode() regains inode_lock before it finally moves
* inode from superblock lists we are OK.
*
diff --git a/fs/super.c b/fs/super.c
index 1943fdf..76dd5b2 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -64,9 +64,6 @@ static struct super_block *alloc_super(struct file_system_type *type)
s = NULL;
goto out;
}
- INIT_LIST_HEAD(&s->s_dirty);
- INIT_LIST_HEAD(&s->s_io);
- INIT_LIST_HEAD(&s->s_more_io);
INIT_LIST_HEAD(&s->s_files);
INIT_LIST_HEAD(&s->s_instances);
INIT_HLIST_HEAD(&s->s_anon);
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 0ec2c59..8719c87 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -40,6 +40,8 @@ enum bdi_stat_item {
#define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
struct backing_dev_info {
+ struct list_head bdi_list;
+
unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
unsigned long state; /* Always use atomic bitops on this */
unsigned int capabilities; /* Device capabilities */
@@ -58,6 +60,10 @@ struct backing_dev_info {
struct device *dev;
+ struct list_head b_dirty; /* dirty inodes */
+ struct list_head b_io; /* parked for writeback */
+ struct list_head b_more_io; /* parked for more writeback */
+
#ifdef CONFIG_DEBUG_FS
struct dentry *debug_dir;
struct dentry *debug_stats;
@@ -72,6 +78,9 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent,
int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
void bdi_unregister(struct backing_dev_info *bdi);
+extern struct mutex bdi_lock;
+extern struct list_head bdi_list;
+
static inline void __add_bdi_stat(struct backing_dev_info *bdi,
enum bdi_stat_item item, s64 amount)
{
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 3b534e5..6b475d4 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -712,7 +712,7 @@ static inline int mapping_writably_mapped(struct address_space *mapping)
struct inode {
struct hlist_node i_hash;
- struct list_head i_list;
+ struct list_head i_list; /* backing dev IO list */
struct list_head i_sb_list;
struct list_head i_dentry;
unsigned long i_ino;
@@ -1329,9 +1329,6 @@ struct super_block {
struct xattr_handler **s_xattr;
struct list_head s_inodes; /* all inodes */
- struct list_head s_dirty; /* dirty inodes */
- struct list_head s_io; /* parked for writeback */
- struct list_head s_more_io; /* parked for more writeback */
struct hlist_head s_anon; /* anonymous dentries for (nfs) exporting */
struct list_head s_files;
/* s_dentry_lru and s_nr_dentry_unused are protected by dcache_lock */
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 493b468..186fdce 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -22,6 +22,8 @@ struct backing_dev_info default_backing_dev_info = {
EXPORT_SYMBOL_GPL(default_backing_dev_info);
static struct class *bdi_class;
+DEFINE_MUTEX(bdi_lock);
+LIST_HEAD(bdi_list);
#ifdef CONFIG_DEBUG_FS
#include <linux/debugfs.h>
@@ -211,6 +213,10 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent,
goto exit;
}
+ mutex_lock(&bdi_lock);
+ list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
+ mutex_unlock(&bdi_lock);
+
bdi->dev = dev;
bdi_debug_register(bdi, dev_name(dev));
@@ -225,9 +231,23 @@ int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)
}
EXPORT_SYMBOL(bdi_register_dev);
+static void bdi_remove_from_list(struct backing_dev_info *bdi)
+{
+ mutex_lock(&bdi_lock);
+ list_del_rcu(&bdi->bdi_list);
+ mutex_unlock(&bdi_lock);
+
+ /*
+ * In case the bdi is freed right after unregister, we need to
+ * make sure any RCU sections have exited
+ */
+ synchronize_rcu();
+}
+
void bdi_unregister(struct backing_dev_info *bdi)
{
if (bdi->dev) {
+ bdi_remove_from_list(bdi);
bdi_debug_unregister(bdi);
device_unregister(bdi->dev);
bdi->dev = NULL;
@@ -245,6 +265,10 @@ int bdi_init(struct backing_dev_info *bdi)
bdi->min_ratio = 0;
bdi->max_ratio = 100;
bdi->max_prop_frac = PROP_FRAC_BASE;
+ INIT_LIST_HEAD(&bdi->bdi_list);
+ INIT_LIST_HEAD(&bdi->b_io);
+ INIT_LIST_HEAD(&bdi->b_dirty);
+ INIT_LIST_HEAD(&bdi->b_more_io);
for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
err = percpu_counter_init(&bdi->bdi_stat[i], 0);
@@ -259,6 +283,8 @@ int bdi_init(struct backing_dev_info *bdi)
err:
while (i--)
percpu_counter_destroy(&bdi->bdi_stat[i]);
+
+ bdi_remove_from_list(bdi);
}
return err;
@@ -269,6 +295,10 @@ void bdi_destroy(struct backing_dev_info *bdi)
{
int i;
+ WARN_ON(!list_empty(&bdi->b_dirty));
+ WARN_ON(!list_empty(&bdi->b_io));
+ WARN_ON(!list_empty(&bdi->b_more_io));
+
bdi_unregister(bdi);
for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index bb553c3..7c44314 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -319,15 +319,13 @@ static void task_dirty_limit(struct task_struct *tsk, long *pdirty)
/*
*
*/
-static DEFINE_SPINLOCK(bdi_lock);
static unsigned int bdi_min_ratio;
int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio)
{
int ret = 0;
- unsigned long flags;
- spin_lock_irqsave(&bdi_lock, flags);
+ mutex_lock(&bdi_lock);
if (min_ratio > bdi->max_ratio) {
ret = -EINVAL;
} else {
@@ -339,27 +337,26 @@ int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio)
ret = -EINVAL;
}
}
- spin_unlock_irqrestore(&bdi_lock, flags);
+ mutex_unlock(&bdi_lock);
return ret;
}
int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned max_ratio)
{
- unsigned long flags;
int ret = 0;
if (max_ratio > 100)
return -EINVAL;
- spin_lock_irqsave(&bdi_lock, flags);
+ mutex_lock(&bdi_lock);
if (bdi->min_ratio > max_ratio) {
ret = -EINVAL;
} else {
bdi->max_ratio = max_ratio;
bdi->max_prop_frac = (PROP_FRAC_BASE * max_ratio) / 100;
}
- spin_unlock_irqrestore(&bdi_lock, flags);
+ mutex_unlock(&bdi_lock);
return ret;
}
--
1.6.3.rc0.1.gf800
^ permalink raw reply related [flat|nested] 27+ messages in thread
* [PATCH 04/12] writeback: switch to per-bdi threads for flushing data
2009-05-25 7:34 [PATCH 0/12] Per-bdi writeback flusher threads #5 Jens Axboe
` (2 preceding siblings ...)
2009-05-25 7:34 ` [PATCH 03/12] writeback: move dirty inodes from super_block to backing_dev_info Jens Axboe
@ 2009-05-25 7:34 ` Jens Axboe
2009-05-25 9:58 ` Jan Kara
2009-05-25 7:34 ` [PATCH 05/12] writeback: get rid of pdflush completely Jens Axboe
` (7 subsequent siblings)
11 siblings, 1 reply; 27+ messages in thread
From: Jens Axboe @ 2009-05-25 7:34 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, hch, akpm, jack, yanmin_zhang, Jens Axboe
This gets rid of pdflush for bdi writeout and kupdated style cleaning.
This is an experiment to see if we get better writeout behaviour with
per-bdi flushing. Some initial tests look pretty encouraging. A sample
ffsb workload that does random writes to files is about 8% faster here
on a simple SATA drive during the benchmark phase. File layout also seems
a LOT more smooth in vmstat:
r b swpd free buff cache si so bi bo in cs us sy id wa
0 1 0 608848 2652 375372 0 0 0 71024 604 24 1 10 48 42
0 1 0 549644 2712 433736 0 0 0 60692 505 27 1 8 48 44
1 0 0 476928 2784 505192 0 0 4 29540 553 24 0 9 53 37
0 1 0 457972 2808 524008 0 0 0 54876 331 16 0 4 38 58
0 1 0 366128 2928 614284 0 0 4 92168 710 58 0 13 53 34
0 1 0 295092 3000 684140 0 0 0 62924 572 23 0 9 53 37
0 1 0 236592 3064 741704 0 0 4 58256 523 17 0 8 48 44
0 1 0 165608 3132 811464 0 0 0 57460 560 21 0 8 54 38
0 1 0 102952 3200 873164 0 0 4 74748 540 29 1 10 48 41
0 1 0 48604 3252 926472 0 0 0 53248 469 29 0 7 47 45
where vanilla tends to fluctuate a lot in the creation phase:
r b swpd free buff cache si so bi bo in cs us sy id wa
1 1 0 678716 5792 303380 0 0 0 74064 565 50 1 11 52 36
1 0 0 662488 5864 319396 0 0 4 352 302 329 0 2 47 51
0 1 0 599312 5924 381468 0 0 0 78164 516 55 0 9 51 40
0 1 0 519952 6008 459516 0 0 4 78156 622 56 1 11 52 37
1 1 0 436640 6092 541632 0 0 0 82244 622 54 0 11 48 41
0 1 0 436640 6092 541660 0 0 0 8 152 39 0 0 51 49
0 1 0 332224 6200 644252 0 0 4 102800 728 46 1 13 49 36
1 0 0 274492 6260 701056 0 0 4 12328 459 49 0 7 50 43
0 1 0 211220 6324 763356 0 0 0 106940 515 37 1 10 51 39
1 0 0 160412 6376 813468 0 0 0 8224 415 43 0 6 49 45
1 1 0 85980 6452 886556 0 0 4 113516 575 39 1 11 54 34
0 2 0 85968 6452 886620 0 0 0 1640 158 211 0 0 46 54
So apart from seemingly behaving better for buffered writeout, this also
allows us to potentially have more than one bdi thread flushing out data.
This may be useful for NUMA type setups.
A 10 disk test with btrfs performs 26% faster with per-bdi flushing. Other
tests pending.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
fs/buffer.c | 2 +-
fs/fs-writeback.c | 316 ++++++++++++++++++++++++++-----------------
fs/sync.c | 2 +-
include/linux/backing-dev.h | 30 ++++
include/linux/fs.h | 3 +-
include/linux/writeback.h | 2 +-
mm/backing-dev.c | 181 +++++++++++++++++++++++--
mm/page-writeback.c | 141 +------------------
mm/vmscan.c | 2 +-
9 files changed, 402 insertions(+), 277 deletions(-)
diff --git a/fs/buffer.c b/fs/buffer.c
index aed2977..14f0802 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -281,7 +281,7 @@ static void free_more_memory(void)
struct zone *zone;
int nid;
- wakeup_pdflush(1024);
+ wakeup_flusher_threads(1024);
yield();
for_each_online_node(nid) {
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 1137408..7cb4d02 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -19,6 +19,8 @@
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/mm.h>
+#include <linux/kthread.h>
+#include <linux/freezer.h>
#include <linux/writeback.h>
#include <linux/blkdev.h>
#include <linux/backing-dev.h>
@@ -61,10 +63,193 @@ int writeback_in_progress(struct backing_dev_info *bdi)
*/
static void writeback_release(struct backing_dev_info *bdi)
{
- BUG_ON(!writeback_in_progress(bdi));
+ WARN_ON_ONCE(!writeback_in_progress(bdi));
+ bdi->wb_arg.nr_pages = 0;
+ bdi->wb_arg.sb = NULL;
clear_bit(BDI_pdflush, &bdi->state);
}
+int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
+ long nr_pages, enum writeback_sync_modes sync_mode)
+{
+ /*
+ * This only happens the first time someone kicks this bdi, so put
+ * it out-of-line.
+ */
+ if (unlikely(!bdi->task)) {
+ bdi_add_default_flusher_task(bdi);
+ return 1;
+ }
+
+ if (writeback_acquire(bdi)) {
+ bdi->wb_arg.nr_pages = nr_pages;
+ bdi->wb_arg.sb = sb;
+ bdi->wb_arg.sync_mode = sync_mode;
+ /*
+ * make above store seen before the task is woken
+ */
+ smp_mb();
+ wake_up(&bdi->wait);
+ }
+
+ return 0;
+}
+
+/*
+ * The maximum number of pages to writeout in a single bdi flush/kupdate
+ * operation. We do this so we don't hold I_SYNC against an inode for
+ * enormous amounts of time, which would block a userspace task which has
+ * been forced to throttle against that inode. Also, the code reevaluates
+ * the dirty each time it has written this many pages.
+ */
+#define MAX_WRITEBACK_PAGES 1024
+
+/*
+ * Periodic writeback of "old" data.
+ *
+ * Define "old": the first time one of an inode's pages is dirtied, we mark the
+ * dirtying-time in the inode's address_space. So this periodic writeback code
+ * just walks the superblock inode list, writing back any inodes which are
+ * older than a specific point in time.
+ *
+ * Try to run once per dirty_writeback_interval. But if a writeback event
+ * takes longer than a dirty_writeback_interval interval, then leave a
+ * one-second gap.
+ *
+ * older_than_this takes precedence over nr_to_write. So we'll only write back
+ * all dirty pages if they are all attached to "old" mappings.
+ */
+static void bdi_kupdated(struct backing_dev_info *bdi)
+{
+ unsigned long oldest_jif;
+ long nr_to_write;
+ struct writeback_control wbc = {
+ .bdi = bdi,
+ .sync_mode = WB_SYNC_NONE,
+ .older_than_this = &oldest_jif,
+ .nr_to_write = 0,
+ .for_kupdate = 1,
+ .range_cyclic = 1,
+ };
+
+ sync_supers();
+
+ oldest_jif = jiffies - msecs_to_jiffies(dirty_expire_interval * 10);
+
+ nr_to_write = global_page_state(NR_FILE_DIRTY) +
+ global_page_state(NR_UNSTABLE_NFS) +
+ (inodes_stat.nr_inodes - inodes_stat.nr_unused);
+
+ while (nr_to_write > 0) {
+ wbc.more_io = 0;
+ wbc.encountered_congestion = 0;
+ wbc.nr_to_write = MAX_WRITEBACK_PAGES;
+ generic_sync_bdi_inodes(NULL, &wbc);
+ if (wbc.nr_to_write > 0)
+ break; /* All the old data is written */
+ nr_to_write -= MAX_WRITEBACK_PAGES;
+ }
+}
+
+static inline bool over_bground_thresh(void)
+{
+ unsigned long background_thresh, dirty_thresh;
+
+ get_dirty_limits(&background_thresh, &dirty_thresh, NULL, NULL);
+
+ return (global_page_state(NR_FILE_DIRTY) +
+ global_page_state(NR_UNSTABLE_NFS) >= background_thresh);
+}
+
+static void bdi_pdflush(struct backing_dev_info *bdi)
+{
+ struct writeback_control wbc = {
+ .bdi = bdi,
+ .sync_mode = bdi->wb_arg.sync_mode,
+ .older_than_this = NULL,
+ .range_cyclic = 1,
+ };
+ long nr_pages = bdi->wb_arg.nr_pages;
+
+ for (;;) {
+ if (wbc.sync_mode == WB_SYNC_NONE && nr_pages <= 0 &&
+ !over_bground_thresh())
+ break;
+
+ wbc.more_io = 0;
+ wbc.encountered_congestion = 0;
+ wbc.nr_to_write = MAX_WRITEBACK_PAGES;
+ wbc.pages_skipped = 0;
+ generic_sync_bdi_inodes(bdi->wb_arg.sb, &wbc);
+ nr_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
+ /*
+ * If we ran out of stuff to write, bail unless more_io got set
+ */
+ if (wbc.nr_to_write > 0 || wbc.pages_skipped > 0) {
+ if (wbc.more_io)
+ continue;
+ break;
+ }
+ }
+}
+
+/*
+ * Handle writeback of dirty data for the device backed by this bdi. Also
+ * wakes up periodically and does kupdated style flushing.
+ */
+int bdi_writeback_task(struct backing_dev_info *bdi)
+{
+ while (!kthread_should_stop()) {
+ unsigned long wait_jiffies;
+ DEFINE_WAIT(wait);
+
+ prepare_to_wait(&bdi->wait, &wait, TASK_INTERRUPTIBLE);
+ wait_jiffies = msecs_to_jiffies(dirty_writeback_interval * 10);
+ schedule_timeout(wait_jiffies);
+ try_to_freeze();
+
+ /*
+ * We get here in two cases:
+ *
+ * schedule_timeout() returned because the dirty writeback
+ * interval has elapsed. If that happens, we will be able
+ * to acquire the writeback lock and will proceed to do
+ * kupdated style writeout.
+ *
+ * Someone called bdi_start_writeback(), which will acquire
+ * the writeback lock. This means our writeback_acquire()
+ * below will fail and we call into bdi_pdflush() for
+ * pdflush style writeout.
+ *
+ */
+ if (writeback_acquire(bdi))
+ bdi_kupdated(bdi);
+ else
+ bdi_pdflush(bdi);
+
+ writeback_release(bdi);
+ finish_wait(&bdi->wait, &wait);
+ }
+
+ return 0;
+}
+
+void bdi_writeback_all(struct super_block *sb, long nr_pages,
+ enum writeback_sync_modes sync_mode)
+{
+ struct backing_dev_info *bdi, *tmp;
+
+ mutex_lock(&bdi_lock);
+
+ list_for_each_entry_safe(bdi, tmp, &bdi_list, bdi_list) {
+ if (!bdi_has_dirty_io(bdi))
+ continue;
+ bdi_start_writeback(bdi, sb, nr_pages, sync_mode);
+ }
+
+ mutex_unlock(&bdi_lock);
+}
+
/**
* __mark_inode_dirty - internal function
* @inode: inode to mark
@@ -263,46 +448,6 @@ static void queue_io(struct backing_dev_info *bdi,
move_expired_inodes(&bdi->b_dirty, &bdi->b_io, older_than_this);
}
-static int sb_on_inode_list(struct super_block *sb, struct list_head *list)
-{
- struct inode *inode;
- int ret = 0;
-
- spin_lock(&inode_lock);
- list_for_each_entry(inode, list, i_list) {
- if (inode->i_sb == sb) {
- ret = 1;
- break;
- }
- }
- spin_unlock(&inode_lock);
- return ret;
-}
-
-int sb_has_dirty_inodes(struct super_block *sb)
-{
- struct backing_dev_info *bdi;
- int ret = 0;
-
- /*
- * This is REALLY expensive right now, but it'll go away
- * when the bdi writeback is introduced
- */
- mutex_lock(&bdi_lock);
- list_for_each_entry(bdi, &bdi_list, bdi_list) {
- if (sb_on_inode_list(sb, &bdi->b_dirty) ||
- sb_on_inode_list(sb, &bdi->b_io) ||
- sb_on_inode_list(sb, &bdi->b_more_io)) {
- ret = 1;
- break;
- }
- }
- mutex_unlock(&bdi_lock);
-
- return ret;
-}
-EXPORT_SYMBOL(sb_has_dirty_inodes);
-
/*
* Write a single inode's dirty pages and inode data out to disk.
* If `wait' is set, wait on the writeout.
@@ -461,11 +606,11 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
return __sync_single_inode(inode, wbc);
}
-static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
- struct writeback_control *wbc,
- struct super_block *sb,
- int is_blkdev_sb)
+void generic_sync_bdi_inodes(struct super_block *sb,
+ struct writeback_control *wbc)
{
+ const int is_blkdev_sb = sb_is_blkdev_sb(sb);
+ struct backing_dev_info *bdi = wbc->bdi;
const unsigned long start = jiffies; /* livelock avoidance */
spin_lock(&inode_lock);
@@ -516,13 +661,6 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
continue; /* Skip a congested blockdev */
}
- if (wbc->bdi && bdi != wbc->bdi) {
- if (!is_blkdev_sb)
- break; /* fs has the wrong queue */
- requeue_io(inode);
- continue; /* blockdev has wrong queue */
- }
-
/*
* Was this inode dirtied after sync_sb_inodes was called?
* This keeps sync from extra jobs and livelock.
@@ -530,16 +668,10 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
if (inode_dirtied_after(inode, start))
break;
- /* Is another pdflush already flushing this queue? */
- if (current_is_pdflush() && !writeback_acquire(bdi))
- break;
-
BUG_ON(inode->i_state & I_FREEING);
__iget(inode);
pages_skipped = wbc->pages_skipped;
__writeback_single_inode(inode, wbc);
- if (current_is_pdflush())
- writeback_release(bdi);
if (wbc->pages_skipped != pages_skipped) {
/*
* writeback is not making progress due to locked
@@ -578,11 +710,6 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
* a variety of queues, so all inodes are searched. For other superblocks,
* assume that all inodes are backed by the same queue.
*
- * FIXME: this linear search could get expensive with many fileystems. But
- * how to fix? We need to go from an address_space to all inodes which share
- * a queue with that address_space. (Easy: have a global "dirty superblocks"
- * list).
- *
* The inodes to be written are parked on bdi->b_io. They are moved back onto
* bdi->b_dirty as they are selected for writing. This way, none can be missed
* on the writer throttling path, and we get decent balancing between many
@@ -591,13 +718,10 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
void generic_sync_sb_inodes(struct super_block *sb,
struct writeback_control *wbc)
{
- const int is_blkdev_sb = sb_is_blkdev_sb(sb);
- struct backing_dev_info *bdi;
-
- mutex_lock(&bdi_lock);
- list_for_each_entry(bdi, &bdi_list, bdi_list)
- generic_sync_bdi_inodes(bdi, wbc, sb, is_blkdev_sb);
- mutex_unlock(&bdi_lock);
+ if (wbc->bdi)
+ generic_sync_bdi_inodes(sb, wbc);
+ else
+ bdi_writeback_all(sb, wbc->nr_to_write, wbc->sync_mode);
if (wbc->sync_mode == WB_SYNC_ALL) {
struct inode *inode, *old_inode = NULL;
@@ -653,58 +777,6 @@ static void sync_sb_inodes(struct super_block *sb,
}
/*
- * Start writeback of dirty pagecache data against all unlocked inodes.
- *
- * Note:
- * We don't need to grab a reference to superblock here. If it has non-empty
- * ->b_dirty it's hadn't been killed yet and kill_super() won't proceed
- * past sync_inodes_sb() until the ->b_dirty/b_io/b_more_io lists are all
- * empty. Since __sync_single_inode() regains inode_lock before it finally moves
- * inode from superblock lists we are OK.
- *
- * If `older_than_this' is non-zero then only flush inodes which have a
- * flushtime older than *older_than_this.
- *
- * If `bdi' is non-zero then we will scan the first inode against each
- * superblock until we find the matching ones. One group will be the dirty
- * inodes against a filesystem. Then when we hit the dummy blockdev superblock,
- * sync_sb_inodes will seekout the blockdev which matches `bdi'. Maybe not
- * super-efficient but we're about to do a ton of I/O...
- */
-void
-writeback_inodes(struct writeback_control *wbc)
-{
- struct super_block *sb;
-
- might_sleep();
- spin_lock(&sb_lock);
-restart:
- list_for_each_entry_reverse(sb, &super_blocks, s_list) {
- if (sb_has_dirty_inodes(sb)) {
- /* we're making our own get_super here */
- sb->s_count++;
- spin_unlock(&sb_lock);
- /*
- * If we can't get the readlock, there's no sense in
- * waiting around, most of the time the FS is going to
- * be unmounted by the time it is released.
- */
- if (down_read_trylock(&sb->s_umount)) {
- if (sb->s_root)
- sync_sb_inodes(sb, wbc);
- up_read(&sb->s_umount);
- }
- spin_lock(&sb_lock);
- if (__put_super_and_need_restart(sb))
- goto restart;
- }
- if (wbc->nr_to_write <= 0)
- break;
- }
- spin_unlock(&sb_lock);
-}
-
-/*
* writeback and wait upon the filesystem's dirty inodes. The caller will
* do this in two passes - one to write, and one to wait.
*
diff --git a/fs/sync.c b/fs/sync.c
index 7abc65f..3887f10 100644
--- a/fs/sync.c
+++ b/fs/sync.c
@@ -23,7 +23,7 @@
*/
static void do_sync(unsigned long wait)
{
- wakeup_pdflush(0);
+ wakeup_flusher_threads(0);
sync_inodes(0); /* All mappings, inodes and their blockdevs */
vfs_dq_sync(NULL);
sync_supers(); /* Write the superblocks */
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 8719c87..f164925 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -13,6 +13,7 @@
#include <linux/proportions.h>
#include <linux/kernel.h>
#include <linux/fs.h>
+#include <linux/writeback.h>
#include <asm/atomic.h>
struct page;
@@ -24,6 +25,7 @@ struct dentry;
*/
enum bdi_state {
BDI_pdflush, /* A pdflush thread is working this device */
+ BDI_pending, /* On its way to being activated */
BDI_async_congested, /* The async (write) queue is getting full */
BDI_sync_congested, /* The sync queue is getting full */
BDI_unused, /* Available bits start here */
@@ -39,6 +41,12 @@ enum bdi_stat_item {
#define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
+struct bdi_writeback_arg {
+ unsigned long nr_pages;
+ struct super_block *sb;
+ enum writeback_sync_modes sync_mode;
+};
+
struct backing_dev_info {
struct list_head bdi_list;
@@ -60,6 +68,9 @@ struct backing_dev_info {
struct device *dev;
+ struct task_struct *task; /* writeback task */
+ wait_queue_head_t wait;
+ struct bdi_writeback_arg wb_arg; /* protected by BDI_pdflush */
struct list_head b_dirty; /* dirty inodes */
struct list_head b_io; /* parked for writeback */
struct list_head b_more_io; /* parked for more writeback */
@@ -77,10 +88,23 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent,
const char *fmt, ...);
int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
void bdi_unregister(struct backing_dev_info *bdi);
+int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
+ long nr_pages, enum writeback_sync_modes sync_mode);
+int bdi_writeback_task(struct backing_dev_info *bdi);
+void bdi_writeback_all(struct super_block *sb, long nr_pages,
+ enum writeback_sync_modes sync_mode);
+void bdi_add_default_flusher_task(struct backing_dev_info *bdi);
extern struct mutex bdi_lock;
extern struct list_head bdi_list;
+static inline int bdi_has_dirty_io(struct backing_dev_info *bdi)
+{
+ return !list_empty(&bdi->b_dirty) ||
+ !list_empty(&bdi->b_io) ||
+ !list_empty(&bdi->b_more_io);
+}
+
static inline void __add_bdi_stat(struct backing_dev_info *bdi,
enum bdi_stat_item item, s64 amount)
{
@@ -196,6 +220,7 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
#define BDI_CAP_EXEC_MAP 0x00000040
#define BDI_CAP_NO_ACCT_WB 0x00000080
#define BDI_CAP_SWAP_BACKED 0x00000100
+#define BDI_CAP_FLUSH_FORKER 0x00000200
#define BDI_CAP_VMFLAGS \
(BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
@@ -265,6 +290,11 @@ static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi)
return bdi->capabilities & BDI_CAP_SWAP_BACKED;
}
+static inline bool bdi_cap_flush_forker(struct backing_dev_info *bdi)
+{
+ return bdi->capabilities & BDI_CAP_FLUSH_FORKER;
+}
+
static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
{
return bdi_cap_writeback_dirty(mapping->backing_dev_info);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 6b475d4..ecdc544 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2063,6 +2063,8 @@ extern int invalidate_inode_pages2_range(struct address_space *mapping,
pgoff_t start, pgoff_t end);
extern void generic_sync_sb_inodes(struct super_block *sb,
struct writeback_control *wbc);
+extern void generic_sync_bdi_inodes(struct super_block *sb,
+ struct writeback_control *);
extern int write_inode_now(struct inode *, int);
extern int filemap_fdatawrite(struct address_space *);
extern int filemap_flush(struct address_space *);
@@ -2180,7 +2182,6 @@ extern int bdev_read_only(struct block_device *);
extern int set_blocksize(struct block_device *, int);
extern int sb_set_blocksize(struct super_block *, int);
extern int sb_min_blocksize(struct super_block *, int);
-extern int sb_has_dirty_inodes(struct super_block *);
extern int generic_file_mmap(struct file *, struct vm_area_struct *);
extern int generic_file_readonly_mmap(struct file *, struct vm_area_struct *);
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 9344547..a8e9f78 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -99,7 +99,7 @@ static inline void inode_sync_wait(struct inode *inode)
/*
* mm/page-writeback.c
*/
-int wakeup_pdflush(long nr_pages);
+void wakeup_flusher_threads(long nr_pages);
void laptop_io_completion(void);
void laptop_sync_completion(void);
void throttle_vm_writeout(gfp_t gfp_mask);
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 186fdce..57c8487 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -1,8 +1,11 @@
#include <linux/wait.h>
#include <linux/backing-dev.h>
+#include <linux/kthread.h>
+#include <linux/freezer.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
+#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/module.h>
#include <linux/writeback.h>
@@ -16,7 +19,7 @@ EXPORT_SYMBOL(default_unplug_io_fn);
struct backing_dev_info default_backing_dev_info = {
.ra_pages = VM_MAX_READAHEAD * 1024 / PAGE_CACHE_SIZE,
.state = 0,
- .capabilities = BDI_CAP_MAP_COPY,
+ .capabilities = BDI_CAP_MAP_COPY | BDI_CAP_FLUSH_FORKER,
.unplug_io_fn = default_unplug_io_fn,
};
EXPORT_SYMBOL_GPL(default_backing_dev_info);
@@ -24,6 +27,7 @@ EXPORT_SYMBOL_GPL(default_backing_dev_info);
static struct class *bdi_class;
DEFINE_MUTEX(bdi_lock);
LIST_HEAD(bdi_list);
+LIST_HEAD(bdi_pending_list);
#ifdef CONFIG_DEBUG_FS
#include <linux/debugfs.h>
@@ -195,6 +199,127 @@ static int __init default_bdi_init(void)
}
subsys_initcall(default_bdi_init);
+static int bdi_start_fn(void *ptr)
+{
+ struct backing_dev_info *bdi = ptr;
+ struct task_struct *tsk = current;
+
+ /*
+ * Add us to the active bdi_list
+ */
+ mutex_lock(&bdi_lock);
+ list_add(&bdi->bdi_list, &bdi_list);
+ mutex_unlock(&bdi_lock);
+
+ tsk->flags |= PF_FLUSHER | PF_SWAPWRITE;
+ set_freezable();
+
+ /*
+ * Our parent may run at a different priority, just set us to normal
+ */
+ set_user_nice(tsk, 0);
+
+ /*
+ * Clear pending bit and wakeup anybody waiting to tear us down
+ */
+ clear_bit(BDI_pending, &bdi->state);
+ smp_mb__after_clear_bit();
+ wake_up_bit(&bdi->state, BDI_pending);
+
+ return bdi_writeback_task(bdi);
+}
+
+static int bdi_forker_task(void *ptr)
+{
+ struct backing_dev_info *me = ptr;
+ DEFINE_WAIT(wait);
+
+ for (;;) {
+ struct backing_dev_info *bdi, *tmp;
+
+ /*
+ * Should never trigger on the default bdi
+ */
+ WARN_ON(bdi_has_dirty_io(me));
+
+ prepare_to_wait(&me->wait, &wait, TASK_INTERRUPTIBLE);
+
+ mutex_lock(&bdi_lock);
+
+ /*
+ * Check if any existing bdi's have dirty data without
+ * a thread registered. If so, set that up.
+ */
+ list_for_each_entry_safe(bdi, tmp, &bdi_list, bdi_list) {
+ if (bdi->task || !bdi_has_dirty_io(bdi))
+ continue;
+
+ bdi_add_default_flusher_task(bdi);
+ }
+
+ if (list_empty(&bdi_pending_list)) {
+ unsigned long wait;
+
+ mutex_unlock(&bdi_lock);
+ wait = msecs_to_jiffies(dirty_writeback_interval * 10);
+ schedule_timeout(wait);
+ try_to_freeze();
+ continue;
+ }
+
+ bdi = list_entry(bdi_pending_list.next, struct backing_dev_info,
+ bdi_list);
+ list_del_init(&bdi->bdi_list);
+ mutex_unlock(&bdi_lock);
+
+ BUG_ON(bdi->task);
+
+ bdi->task = kthread_run(bdi_start_fn, bdi, "bdi-%s",
+ dev_name(bdi->dev));
+ /*
+ * If task creation fails, then readd the bdi to
+ * the pending list and force writeout of the bdi
+ * from this forker thread. That will free some memory
+ * and we can try again.
+ */
+ if (!bdi->task) {
+ struct writeback_control wbc = {
+ .bdi = bdi,
+ .sync_mode = WB_SYNC_NONE,
+ .older_than_this = NULL,
+ .range_cyclic = 1,
+ };
+
+ /*
+ * Add this 'bdi' to the back, so we get
+ * a chance to flush other bdi's to free
+ * memory.
+ */
+ mutex_lock(&bdi_lock);
+ list_add_tail(&bdi->bdi_list, &bdi_pending_list);
+ mutex_unlock(&bdi_lock);
+
+ wbc.nr_to_write = 1024;
+ generic_sync_bdi_inodes(NULL, &wbc);
+ }
+ }
+
+ finish_wait(&me->wait, &wait);
+ return 0;
+}
+
+void bdi_add_default_flusher_task(struct backing_dev_info *bdi)
+{
+ if (test_and_set_bit(BDI_pending, &bdi->state))
+ return;
+
+ mutex_lock(&bdi_lock);
+ list_move_tail(&bdi->bdi_list, &bdi_pending_list);
+ mutex_unlock(&bdi_lock);
+
+ wake_up(&default_backing_dev_info.wait);
+}
+
int bdi_register(struct backing_dev_info *bdi, struct device *parent,
const char *fmt, ...)
{
@@ -214,12 +339,29 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent,
}
mutex_lock(&bdi_lock);
- list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
+ list_add_tail(&bdi->bdi_list, &bdi_list);
mutex_unlock(&bdi_lock);
bdi->dev = dev;
- bdi_debug_register(bdi, dev_name(dev));
+ /*
+ * Just start the forker thread for our default backing_dev_info,
+ * and add other bdi's to the list. They will get a thread created
+ * on-demand when they need it.
+ */
+ if (bdi_cap_flush_forker(bdi)) {
+ bdi->task = kthread_run(bdi_forker_task, bdi, "bdi-%s",
+ dev_name(dev));
+ if (!bdi->task) {
+ mutex_lock(&bdi_lock);
+ list_del(&bdi->bdi_list);
+ mutex_unlock(&bdi_lock);
+ ret = -ENOMEM;
+ goto exit;
+ }
+ }
+
+ bdi_debug_register(bdi, dev_name(dev));
exit:
return ret;
}
@@ -231,23 +373,34 @@ int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)
}
EXPORT_SYMBOL(bdi_register_dev);
-static void bdi_remove_from_list(struct backing_dev_info *bdi)
+static int sched_wait(void *word)
{
- mutex_lock(&bdi_lock);
- list_del_rcu(&bdi->bdi_list);
- mutex_unlock(&bdi_lock);
+ schedule();
+ return 0;
+}
+static void bdi_wb_shutdown(struct backing_dev_info *bdi)
+{
/*
- * In case the bdi is freed right after unregister, we need to
- * make sure any RCU sections have exited
+ * If setup is pending, wait for that to complete first
*/
- synchronize_rcu();
+ wait_on_bit(&bdi->state, BDI_pending, sched_wait, TASK_UNINTERRUPTIBLE);
+
+ mutex_lock(&bdi_lock);
+ list_del(&bdi->bdi_list);
+ mutex_unlock(&bdi_lock);
}
void bdi_unregister(struct backing_dev_info *bdi)
{
if (bdi->dev) {
- bdi_remove_from_list(bdi);
+ if (!bdi_cap_flush_forker(bdi)) {
+ bdi_wb_shutdown(bdi);
+ if (bdi->task) {
+ kthread_stop(bdi->task);
+ bdi->task = NULL;
+ }
+ }
bdi_debug_unregister(bdi);
device_unregister(bdi->dev);
bdi->dev = NULL;
@@ -257,14 +410,14 @@ EXPORT_SYMBOL(bdi_unregister);
int bdi_init(struct backing_dev_info *bdi)
{
- int i;
- int err;
+ int i, err;
bdi->dev = NULL;
bdi->min_ratio = 0;
bdi->max_ratio = 100;
bdi->max_prop_frac = PROP_FRAC_BASE;
+ init_waitqueue_head(&bdi->wait);
INIT_LIST_HEAD(&bdi->bdi_list);
INIT_LIST_HEAD(&bdi->b_io);
INIT_LIST_HEAD(&bdi->b_dirty);
@@ -283,8 +436,6 @@ int bdi_init(struct backing_dev_info *bdi)
err:
while (i--)
percpu_counter_destroy(&bdi->bdi_stat[i]);
-
- bdi_remove_from_list(bdi);
}
return err;
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 7c44314..54a4a65 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -36,15 +36,6 @@
#include <linux/pagevec.h>
/*
- * The maximum number of pages to writeout in a single bdflush/kupdate
- * operation. We do this so we don't hold I_SYNC against an inode for
- * enormous amounts of time, which would block a userspace task which has
- * been forced to throttle against that inode. Also, the code reevaluates
- * the dirty each time it has written this many pages.
- */
-#define MAX_WRITEBACK_PAGES 1024
-
-/*
* After a CPU has dirtied this many pages, balance_dirty_pages_ratelimited
* will look to see if it needs to force writeback or throttling.
*/
@@ -117,8 +108,6 @@ EXPORT_SYMBOL(laptop_mode);
/* End of sysctl-exported parameters */
-static void background_writeout(unsigned long _min_pages);
-
/*
* Scale the writeback cache size proportional to the relative writeout speeds.
*
@@ -539,7 +528,7 @@ static void balance_dirty_pages(struct address_space *mapping)
* been flushed to permanent storage.
*/
if (bdi_nr_reclaimable) {
- writeback_inodes(&wbc);
+ generic_sync_bdi_inodes(NULL, &wbc);
pages_written += write_chunk - wbc.nr_to_write;
get_dirty_limits(&background_thresh, &dirty_thresh,
&bdi_thresh, bdi);
@@ -590,7 +579,7 @@ static void balance_dirty_pages(struct address_space *mapping)
(!laptop_mode && (global_page_state(NR_FILE_DIRTY)
+ global_page_state(NR_UNSTABLE_NFS)
> background_thresh)))
- pdflush_operation(background_writeout, 0);
+ bdi_start_writeback(bdi, NULL, 0, WB_SYNC_NONE);
}
void set_page_dirty_balance(struct page *page, int page_mkwrite)
@@ -675,152 +664,36 @@ void throttle_vm_writeout(gfp_t gfp_mask)
}
/*
- * writeback at least _min_pages, and keep writing until the amount of dirty
- * memory is less than the background threshold, or until we're all clean.
- */
-static void background_writeout(unsigned long _min_pages)
-{
- long min_pages = _min_pages;
- struct writeback_control wbc = {
- .bdi = NULL,
- .sync_mode = WB_SYNC_NONE,
- .older_than_this = NULL,
- .nr_to_write = 0,
- .nonblocking = 1,
- .range_cyclic = 1,
- };
-
- for ( ; ; ) {
- unsigned long background_thresh;
- unsigned long dirty_thresh;
-
- get_dirty_limits(&background_thresh, &dirty_thresh, NULL, NULL);
- if (global_page_state(NR_FILE_DIRTY) +
- global_page_state(NR_UNSTABLE_NFS) < background_thresh
- && min_pages <= 0)
- break;
- wbc.more_io = 0;
- wbc.encountered_congestion = 0;
- wbc.nr_to_write = MAX_WRITEBACK_PAGES;
- wbc.pages_skipped = 0;
- writeback_inodes(&wbc);
- min_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
- if (wbc.nr_to_write > 0 || wbc.pages_skipped > 0) {
- /* Wrote less than expected */
- if (wbc.encountered_congestion || wbc.more_io)
- congestion_wait(WRITE, HZ/10);
- else
- break;
- }
- }
-}
-
-/*
* Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back
* the whole world. Returns 0 if a pdflush thread was dispatched. Returns
* -1 if all pdflush threads were busy.
*/
-int wakeup_pdflush(long nr_pages)
+void wakeup_flusher_threads(long nr_pages)
{
if (nr_pages == 0)
nr_pages = global_page_state(NR_FILE_DIRTY) +
global_page_state(NR_UNSTABLE_NFS);
- return pdflush_operation(background_writeout, nr_pages);
+ bdi_writeback_all(NULL, nr_pages, WB_SYNC_NONE);
+ return;
}
-static void wb_timer_fn(unsigned long unused);
static void laptop_timer_fn(unsigned long unused);
-static DEFINE_TIMER(wb_timer, wb_timer_fn, 0, 0);
static DEFINE_TIMER(laptop_mode_wb_timer, laptop_timer_fn, 0, 0);
/*
- * Periodic writeback of "old" data.
- *
- * Define "old": the first time one of an inode's pages is dirtied, we mark the
- * dirtying-time in the inode's address_space. So this periodic writeback code
- * just walks the superblock inode list, writing back any inodes which are
- * older than a specific point in time.
- *
- * Try to run once per dirty_writeback_interval. But if a writeback event
- * takes longer than a dirty_writeback_interval interval, then leave a
- * one-second gap.
- *
- * older_than_this takes precedence over nr_to_write. So we'll only write back
- * all dirty pages if they are all attached to "old" mappings.
- */
-static void wb_kupdate(unsigned long arg)
-{
- unsigned long oldest_jif;
- unsigned long start_jif;
- unsigned long next_jif;
- long nr_to_write;
- struct writeback_control wbc = {
- .bdi = NULL,
- .sync_mode = WB_SYNC_NONE,
- .older_than_this = &oldest_jif,
- .nr_to_write = 0,
- .nonblocking = 1,
- .for_kupdate = 1,
- .range_cyclic = 1,
- };
-
- sync_supers();
-
- oldest_jif = jiffies - msecs_to_jiffies(dirty_expire_interval * 10);
- start_jif = jiffies;
- next_jif = start_jif + msecs_to_jiffies(dirty_writeback_interval * 10);
- nr_to_write = global_page_state(NR_FILE_DIRTY) +
- global_page_state(NR_UNSTABLE_NFS) +
- (inodes_stat.nr_inodes - inodes_stat.nr_unused);
- while (nr_to_write > 0) {
- wbc.more_io = 0;
- wbc.encountered_congestion = 0;
- wbc.nr_to_write = MAX_WRITEBACK_PAGES;
- writeback_inodes(&wbc);
- if (wbc.nr_to_write > 0) {
- if (wbc.encountered_congestion || wbc.more_io)
- congestion_wait(WRITE, HZ/10);
- else
- break; /* All the old data is written */
- }
- nr_to_write -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
- }
- if (time_before(next_jif, jiffies + HZ))
- next_jif = jiffies + HZ;
- if (dirty_writeback_interval)
- mod_timer(&wb_timer, next_jif);
-}
-
-/*
* sysctl handler for /proc/sys/vm/dirty_writeback_centisecs
*/
int dirty_writeback_centisecs_handler(ctl_table *table, int write,
struct file *file, void __user *buffer, size_t *length, loff_t *ppos)
{
proc_dointvec(table, write, file, buffer, length, ppos);
- if (dirty_writeback_interval)
- mod_timer(&wb_timer, jiffies +
- msecs_to_jiffies(dirty_writeback_interval * 10));
- else
- del_timer(&wb_timer);
return 0;
}
-static void wb_timer_fn(unsigned long unused)
-{
- if (pdflush_operation(wb_kupdate, 0) < 0)
- mod_timer(&wb_timer, jiffies + HZ); /* delay 1 second */
-}
-
-static void laptop_flush(unsigned long unused)
-{
- sys_sync();
-}
-
static void laptop_timer_fn(unsigned long unused)
{
- pdflush_operation(laptop_flush, 0);
+ wakeup_flusher_threads(0);
}
/*
@@ -903,8 +776,6 @@ void __init page_writeback_init(void)
{
int shift;
- mod_timer(&wb_timer,
- jiffies + msecs_to_jiffies(dirty_writeback_interval * 10));
writeback_set_ratelimit();
register_cpu_notifier(&ratelimit_nb);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 5fa3eda..e37fd38 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1654,7 +1654,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
*/
if (total_scanned > sc->swap_cluster_max +
sc->swap_cluster_max / 2) {
- wakeup_pdflush(laptop_mode ? 0 : total_scanned);
+ wakeup_flusher_threads(laptop_mode ? 0 : total_scanned);
sc->may_writepage = 1;
}
--
1.6.3.rc0.1.gf800
^ permalink raw reply related [flat|nested] 27+ messages in thread
* [PATCH 05/12] writeback: get rid of pdflush completely
2009-05-25 7:34 [PATCH 0/12] Per-bdi writeback flusher threads #5 Jens Axboe
` (3 preceding siblings ...)
2009-05-25 7:34 ` [PATCH 04/12] writeback: switch to per-bdi threads for flushing data Jens Axboe
@ 2009-05-25 7:34 ` Jens Axboe
2009-05-25 7:34 ` [PATCH 06/12] writeback: separate the flushing state/task from the bdi Jens Axboe
` (6 subsequent siblings)
11 siblings, 0 replies; 27+ messages in thread
From: Jens Axboe @ 2009-05-25 7:34 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, hch, akpm, jack, yanmin_zhang, Jens Axboe
It is now unused, so kill it off.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
fs/fs-writeback.c | 5 +
include/linux/writeback.h | 12 --
mm/Makefile | 2 +-
mm/pdflush.c | 269 ---------------------------------------------
4 files changed, 6 insertions(+), 282 deletions(-)
delete mode 100644 mm/pdflush.c
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 7cb4d02..ca4d9da 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -29,6 +29,11 @@
#define inode_to_bdi(inode) ((inode)->i_mapping->backing_dev_info)
+/*
+ * We don't actually have pdflush, but this one is exported though /proc...
+ */
+int nr_pdflush_threads;
+
/**
* writeback_acquire - attempt to get exclusive writeback access to a device
* @bdi: the device's backing_dev_info structure
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index a8e9f78..baf04a9 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -14,17 +14,6 @@ extern struct list_head inode_in_use;
extern struct list_head inode_unused;
/*
- * Yes, writeback.h requires sched.h
- * No, sched.h is not included from here.
- */
-static inline int task_is_pdflush(struct task_struct *task)
-{
- return task->flags & PF_FLUSHER;
-}
-
-#define current_is_pdflush() task_is_pdflush(current)
-
-/*
* fs/fs-writeback.c
*/
enum writeback_sync_modes {
@@ -151,7 +140,6 @@ balance_dirty_pages_ratelimited(struct address_space *mapping)
typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
void *data);
-int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0);
int generic_writepages(struct address_space *mapping,
struct writeback_control *wbc);
int write_cache_pages(struct address_space *mapping,
diff --git a/mm/Makefile b/mm/Makefile
index ec73c68..2adb811 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -8,7 +8,7 @@ mmu-$(CONFIG_MMU) := fremap.o highmem.o madvise.o memory.o mincore.o \
vmalloc.o
obj-y := bootmem.o filemap.o mempool.o oom_kill.o fadvise.o \
- maccess.o page_alloc.o page-writeback.o pdflush.o \
+ maccess.o page_alloc.o page-writeback.o \
readahead.o swap.o truncate.o vmscan.o shmem.o \
prio_tree.o util.o mmzone.o vmstat.o backing-dev.o \
page_isolation.o mm_init.o $(mmu-y)
diff --git a/mm/pdflush.c b/mm/pdflush.c
deleted file mode 100644
index 235ac44..0000000
--- a/mm/pdflush.c
+++ /dev/null
@@ -1,269 +0,0 @@
-/*
- * mm/pdflush.c - worker threads for writing back filesystem data
- *
- * Copyright (C) 2002, Linus Torvalds.
- *
- * 09Apr2002 Andrew Morton
- * Initial version
- * 29Feb2004 kaos@sgi.com
- * Move worker thread creation to kthread to avoid chewing
- * up stack space with nested calls to kernel_thread.
- */
-
-#include <linux/sched.h>
-#include <linux/list.h>
-#include <linux/signal.h>
-#include <linux/spinlock.h>
-#include <linux/gfp.h>
-#include <linux/init.h>
-#include <linux/module.h>
-#include <linux/fs.h> /* Needed by writeback.h */
-#include <linux/writeback.h> /* Prototypes pdflush_operation() */
-#include <linux/kthread.h>
-#include <linux/cpuset.h>
-#include <linux/freezer.h>
-
-
-/*
- * Minimum and maximum number of pdflush instances
- */
-#define MIN_PDFLUSH_THREADS 2
-#define MAX_PDFLUSH_THREADS 8
-
-static void start_one_pdflush_thread(void);
-
-
-/*
- * The pdflush threads are worker threads for writing back dirty data.
- * Ideally, we'd like one thread per active disk spindle. But the disk
- * topology is very hard to divine at this level. Instead, we take
- * care in various places to prevent more than one pdflush thread from
- * performing writeback against a single filesystem. pdflush threads
- * have the PF_FLUSHER flag set in current->flags to aid in this.
- */
-
-/*
- * All the pdflush threads. Protected by pdflush_lock
- */
-static LIST_HEAD(pdflush_list);
-static DEFINE_SPINLOCK(pdflush_lock);
-
-/*
- * The count of currently-running pdflush threads. Protected
- * by pdflush_lock.
- *
- * Readable by sysctl, but not writable. Published to userspace at
- * /proc/sys/vm/nr_pdflush_threads.
- */
-int nr_pdflush_threads = 0;
-
-/*
- * The time at which the pdflush thread pool last went empty
- */
-static unsigned long last_empty_jifs;
-
-/*
- * The pdflush thread.
- *
- * Thread pool management algorithm:
- *
- * - The minimum and maximum number of pdflush instances are bound
- * by MIN_PDFLUSH_THREADS and MAX_PDFLUSH_THREADS.
- *
- * - If there have been no idle pdflush instances for 1 second, create
- * a new one.
- *
- * - If the least-recently-went-to-sleep pdflush thread has been asleep
- * for more than one second, terminate a thread.
- */
-
-/*
- * A structure for passing work to a pdflush thread. Also for passing
- * state information between pdflush threads. Protected by pdflush_lock.
- */
-struct pdflush_work {
- struct task_struct *who; /* The thread */
- void (*fn)(unsigned long); /* A callback function */
- unsigned long arg0; /* An argument to the callback */
- struct list_head list; /* On pdflush_list, when idle */
- unsigned long when_i_went_to_sleep;
-};
-
-static int __pdflush(struct pdflush_work *my_work)
-{
- current->flags |= PF_FLUSHER | PF_SWAPWRITE;
- set_freezable();
- my_work->fn = NULL;
- my_work->who = current;
- INIT_LIST_HEAD(&my_work->list);
-
- spin_lock_irq(&pdflush_lock);
- for ( ; ; ) {
- struct pdflush_work *pdf;
-
- set_current_state(TASK_INTERRUPTIBLE);
- list_move(&my_work->list, &pdflush_list);
- my_work->when_i_went_to_sleep = jiffies;
- spin_unlock_irq(&pdflush_lock);
- schedule();
- try_to_freeze();
- spin_lock_irq(&pdflush_lock);
- if (!list_empty(&my_work->list)) {
- /*
- * Someone woke us up, but without removing our control
- * structure from the global list. swsusp will do this
- * in try_to_freeze()->refrigerator(). Handle it.
- */
- my_work->fn = NULL;
- continue;
- }
- if (my_work->fn == NULL) {
- printk("pdflush: bogus wakeup\n");
- continue;
- }
- spin_unlock_irq(&pdflush_lock);
-
- (*my_work->fn)(my_work->arg0);
-
- spin_lock_irq(&pdflush_lock);
-
- /*
- * Thread creation: For how long have there been zero
- * available threads?
- *
- * To throttle creation, we reset last_empty_jifs.
- */
- if (time_after(jiffies, last_empty_jifs + 1 * HZ)) {
- if (list_empty(&pdflush_list)) {
- if (nr_pdflush_threads < MAX_PDFLUSH_THREADS) {
- last_empty_jifs = jiffies;
- nr_pdflush_threads++;
- spin_unlock_irq(&pdflush_lock);
- start_one_pdflush_thread();
- spin_lock_irq(&pdflush_lock);
- }
- }
- }
-
- my_work->fn = NULL;
-
- /*
- * Thread destruction: For how long has the sleepiest
- * thread slept?
- */
- if (list_empty(&pdflush_list))
- continue;
- if (nr_pdflush_threads <= MIN_PDFLUSH_THREADS)
- continue;
- pdf = list_entry(pdflush_list.prev, struct pdflush_work, list);
- if (time_after(jiffies, pdf->when_i_went_to_sleep + 1 * HZ)) {
- /* Limit exit rate */
- pdf->when_i_went_to_sleep = jiffies;
- break; /* exeunt */
- }
- }
- nr_pdflush_threads--;
- spin_unlock_irq(&pdflush_lock);
- return 0;
-}
-
-/*
- * Of course, my_work wants to be just a local in __pdflush(). It is
- * separated out in this manner to hopefully prevent the compiler from
- * performing unfortunate optimisations against the auto variables. Because
- * these are visible to other tasks and CPUs. (No problem has actually
- * been observed. This is just paranoia).
- */
-static int pdflush(void *dummy)
-{
- struct pdflush_work my_work;
- cpumask_var_t cpus_allowed;
-
- /*
- * Since the caller doesn't even check kthread_run() worked, let's not
- * freak out too much if this fails.
- */
- if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
- printk(KERN_WARNING "pdflush failed to allocate cpumask\n");
- return 0;
- }
-
- /*
- * pdflush can spend a lot of time doing encryption via dm-crypt. We
- * don't want to do that at keventd's priority.
- */
- set_user_nice(current, 0);
-
- /*
- * Some configs put our parent kthread in a limited cpuset,
- * which kthread() overrides, forcing cpus_allowed == cpu_all_mask.
- * Our needs are more modest - cut back to our cpusets cpus_allowed.
- * This is needed as pdflush's are dynamically created and destroyed.
- * The boottime pdflush's are easily placed w/o these 2 lines.
- */
- cpuset_cpus_allowed(current, cpus_allowed);
- set_cpus_allowed_ptr(current, cpus_allowed);
- free_cpumask_var(cpus_allowed);
-
- return __pdflush(&my_work);
-}
-
-/*
- * Attempt to wake up a pdflush thread, and get it to do some work for you.
- * Returns zero if it indeed managed to find a worker thread, and passed your
- * payload to it.
- */
-int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0)
-{
- unsigned long flags;
- int ret = 0;
-
- BUG_ON(fn == NULL); /* Hard to diagnose if it's deferred */
-
- spin_lock_irqsave(&pdflush_lock, flags);
- if (list_empty(&pdflush_list)) {
- ret = -1;
- } else {
- struct pdflush_work *pdf;
-
- pdf = list_entry(pdflush_list.next, struct pdflush_work, list);
- list_del_init(&pdf->list);
- if (list_empty(&pdflush_list))
- last_empty_jifs = jiffies;
- pdf->fn = fn;
- pdf->arg0 = arg0;
- wake_up_process(pdf->who);
- }
- spin_unlock_irqrestore(&pdflush_lock, flags);
-
- return ret;
-}
-
-static void start_one_pdflush_thread(void)
-{
- struct task_struct *k;
-
- k = kthread_run(pdflush, NULL, "pdflush");
- if (unlikely(IS_ERR(k))) {
- spin_lock_irq(&pdflush_lock);
- nr_pdflush_threads--;
- spin_unlock_irq(&pdflush_lock);
- }
-}
-
-static int __init pdflush_init(void)
-{
- int i;
-
- /*
- * Pre-set nr_pdflush_threads... If we fail to create,
- * the count will be decremented.
- */
- nr_pdflush_threads = MIN_PDFLUSH_THREADS;
-
- for (i = 0; i < MIN_PDFLUSH_THREADS; i++)
- start_one_pdflush_thread();
- return 0;
-}
-
-module_init(pdflush_init);
--
1.6.3.rc0.1.gf800
^ permalink raw reply related [flat|nested] 27+ messages in thread
* [PATCH 06/12] writeback: separate the flushing state/task from the bdi
2009-05-25 7:34 [PATCH 0/12] Per-bdi writeback flusher threads #5 Jens Axboe
` (4 preceding siblings ...)
2009-05-25 7:34 ` [PATCH 05/12] writeback: get rid of pdflush completely Jens Axboe
@ 2009-05-25 7:34 ` Jens Axboe
2009-05-25 10:13 ` Jan Kara
2009-05-25 7:34 ` [PATCH 07/12] writeback: support > 1 flusher thread per bdi Jens Axboe
` (5 subsequent siblings)
11 siblings, 1 reply; 27+ messages in thread
From: Jens Axboe @ 2009-05-25 7:34 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, hch, akpm, jack, yanmin_zhang, Jens Axboe
Add a struct bdi_writeback for tracking and handling dirty IO. This
is in preparation for adding > 1 flusher task per bdi.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
fs/fs-writeback.c | 145 ++++++++++++++++++++++++---------------
include/linux/backing-dev.h | 40 ++++++-----
mm/backing-dev.c | 161 ++++++++++++++++++++++++++++++++-----------
3 files changed, 233 insertions(+), 113 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index ca4d9da..7a9f0b0 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -46,9 +46,11 @@ int nr_pdflush_threads;
* unless they implement their own. Which is somewhat inefficient, as this
* may prevent concurrent writeback against multiple devices.
*/
-static int writeback_acquire(struct backing_dev_info *bdi)
+static int writeback_acquire(struct bdi_writeback *wb)
{
- return !test_and_set_bit(BDI_pdflush, &bdi->state);
+ struct backing_dev_info *bdi = wb->bdi;
+
+ return !test_and_set_bit(wb->nr, &bdi->wb_active);
}
/**
@@ -59,19 +61,40 @@ static int writeback_acquire(struct backing_dev_info *bdi)
*/
int writeback_in_progress(struct backing_dev_info *bdi)
{
- return test_bit(BDI_pdflush, &bdi->state);
+ return bdi->wb_active != 0;
}
/**
* writeback_release - relinquish exclusive writeback access against a device.
* @bdi: the device's backing_dev_info structure
*/
-static void writeback_release(struct backing_dev_info *bdi)
+static void writeback_release(struct bdi_writeback *wb)
{
- WARN_ON_ONCE(!writeback_in_progress(bdi));
- bdi->wb_arg.nr_pages = 0;
- bdi->wb_arg.sb = NULL;
- clear_bit(BDI_pdflush, &bdi->state);
+ struct backing_dev_info *bdi = wb->bdi;
+
+ wb->nr_pages = 0;
+ wb->sb = NULL;
+ clear_bit(wb->nr, &bdi->wb_active);
+}
+
+static void wb_start_writeback(struct bdi_writeback *wb, struct super_block *sb,
+ long nr_pages,
+ enum writeback_sync_modes sync_mode)
+{
+ if (!wb_has_dirty_io(wb))
+ return;
+
+ if (writeback_acquire(wb)) {
+ wb->nr_pages = nr_pages;
+ wb->sb = sb;
+ wb->sync_mode = sync_mode;
+
+ /*
+ * make above store seen before the task is woken
+ */
+ smp_mb();
+ wake_up(&wb->wait);
+ }
}
int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
@@ -81,22 +104,12 @@ int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
* This only happens the first time someone kicks this bdi, so put
* it out-of-line.
*/
- if (unlikely(!bdi->task)) {
+ if (unlikely(!bdi->wb.task)) {
bdi_add_default_flusher_task(bdi);
return 1;
}
- if (writeback_acquire(bdi)) {
- bdi->wb_arg.nr_pages = nr_pages;
- bdi->wb_arg.sb = sb;
- bdi->wb_arg.sync_mode = sync_mode;
- /*
- * make above store seen before the task is woken
- */
- smp_mb();
- wake_up(&bdi->wait);
- }
-
+ wb_start_writeback(&bdi->wb, sb, nr_pages, sync_mode);
return 0;
}
@@ -124,12 +137,12 @@ int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
* older_than_this takes precedence over nr_to_write. So we'll only write back
* all dirty pages if they are all attached to "old" mappings.
*/
-static void bdi_kupdated(struct backing_dev_info *bdi)
+static void wb_kupdated(struct bdi_writeback *wb)
{
unsigned long oldest_jif;
long nr_to_write;
struct writeback_control wbc = {
- .bdi = bdi,
+ .bdi = wb->bdi,
.sync_mode = WB_SYNC_NONE,
.older_than_this = &oldest_jif,
.nr_to_write = 0,
@@ -166,15 +179,19 @@ static inline bool over_bground_thresh(void)
global_page_state(NR_UNSTABLE_NFS) >= background_thresh);
}
-static void bdi_pdflush(struct backing_dev_info *bdi)
+static void generic_sync_wb_inodes(struct bdi_writeback *wb,
+ struct super_block *sb,
+ struct writeback_control *wbc);
+
+static void wb_writeback(struct bdi_writeback *wb)
{
struct writeback_control wbc = {
- .bdi = bdi,
- .sync_mode = bdi->wb_arg.sync_mode,
+ .bdi = wb->bdi,
+ .sync_mode = wb->sync_mode,
.older_than_this = NULL,
.range_cyclic = 1,
};
- long nr_pages = bdi->wb_arg.nr_pages;
+ long nr_pages = wb->nr_pages;
for (;;) {
if (wbc.sync_mode == WB_SYNC_NONE && nr_pages <= 0 &&
@@ -185,7 +202,7 @@ static void bdi_pdflush(struct backing_dev_info *bdi)
wbc.encountered_congestion = 0;
wbc.nr_to_write = MAX_WRITEBACK_PAGES;
wbc.pages_skipped = 0;
- generic_sync_bdi_inodes(bdi->wb_arg.sb, &wbc);
+ generic_sync_wb_inodes(wb, wb->sb, &wbc);
nr_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
/*
* If we ran out of stuff to write, bail unless more_io got set
@@ -202,13 +219,13 @@ static void bdi_pdflush(struct backing_dev_info *bdi)
* Handle writeback of dirty data for the device backed by this bdi. Also
* wakes up periodically and does kupdated style flushing.
*/
-int bdi_writeback_task(struct backing_dev_info *bdi)
+int bdi_writeback_task(struct bdi_writeback *wb)
{
while (!kthread_should_stop()) {
unsigned long wait_jiffies;
DEFINE_WAIT(wait);
- prepare_to_wait(&bdi->wait, &wait, TASK_INTERRUPTIBLE);
+ prepare_to_wait(&wb->wait, &wait, TASK_INTERRUPTIBLE);
wait_jiffies = msecs_to_jiffies(dirty_writeback_interval * 10);
schedule_timeout(wait_jiffies);
try_to_freeze();
@@ -227,13 +244,13 @@ int bdi_writeback_task(struct backing_dev_info *bdi)
* pdflush style writeout.
*
*/
- if (writeback_acquire(bdi))
- bdi_kupdated(bdi);
+ if (writeback_acquire(wb))
+ wb_kupdated(wb);
else
- bdi_pdflush(bdi);
+ wb_writeback(wb);
- writeback_release(bdi);
- finish_wait(&bdi->wait, &wait);
+ writeback_release(wb);
+ finish_wait(&wb->wait, &wait);
}
return 0;
@@ -255,6 +272,14 @@ void bdi_writeback_all(struct super_block *sb, long nr_pages,
mutex_unlock(&bdi_lock);
}
+/*
+ * We have only a single wb per bdi, so just return that.
+ */
+static inline struct bdi_writeback *inode_get_wb(struct inode *inode)
+{
+ return &inode_to_bdi(inode)->wb;
+}
+
/**
* __mark_inode_dirty - internal function
* @inode: inode to mark
@@ -353,9 +378,10 @@ void __mark_inode_dirty(struct inode *inode, int flags)
* reposition it (that would break b_dirty time-ordering).
*/
if (!was_dirty) {
+ struct bdi_writeback *wb = inode_get_wb(inode);
+
inode->dirtied_when = jiffies;
- list_move(&inode->i_list,
- &inode_to_bdi(inode)->b_dirty);
+ list_move(&inode->i_list, &wb->b_dirty);
}
}
out:
@@ -382,16 +408,16 @@ static int write_inode(struct inode *inode, int sync)
*/
static void redirty_tail(struct inode *inode)
{
- struct backing_dev_info *bdi = inode_to_bdi(inode);
+ struct bdi_writeback *wb = inode_get_wb(inode);
- if (!list_empty(&bdi->b_dirty)) {
+ if (!list_empty(&wb->b_dirty)) {
struct inode *tail;
- tail = list_entry(bdi->b_dirty.next, struct inode, i_list);
+ tail = list_entry(wb->b_dirty.next, struct inode, i_list);
if (time_before(inode->dirtied_when, tail->dirtied_when))
inode->dirtied_when = jiffies;
}
- list_move(&inode->i_list, &bdi->b_dirty);
+ list_move(&inode->i_list, &wb->b_dirty);
}
/*
@@ -399,7 +425,9 @@ static void redirty_tail(struct inode *inode)
*/
static void requeue_io(struct inode *inode)
{
- list_move(&inode->i_list, &inode_to_bdi(inode)->b_more_io);
+ struct bdi_writeback *wb = inode_get_wb(inode);
+
+ list_move(&inode->i_list, &wb->b_more_io);
}
static void inode_sync_complete(struct inode *inode)
@@ -446,11 +474,10 @@ static void move_expired_inodes(struct list_head *delaying_queue,
/*
* Queue all expired dirty inodes for io, eldest first.
*/
-static void queue_io(struct backing_dev_info *bdi,
- unsigned long *older_than_this)
+static void queue_io(struct bdi_writeback *wb, unsigned long *older_than_this)
{
- list_splice_init(&bdi->b_more_io, bdi->b_io.prev);
- move_expired_inodes(&bdi->b_dirty, &bdi->b_io, older_than_this);
+ list_splice_init(&wb->b_more_io, wb->b_io.prev);
+ move_expired_inodes(&wb->b_dirty, &wb->b_io, older_than_this);
}
/*
@@ -611,20 +638,20 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
return __sync_single_inode(inode, wbc);
}
-void generic_sync_bdi_inodes(struct super_block *sb,
- struct writeback_control *wbc)
+static void generic_sync_wb_inodes(struct bdi_writeback *wb,
+ struct super_block *sb,
+ struct writeback_control *wbc)
{
const int is_blkdev_sb = sb_is_blkdev_sb(sb);
- struct backing_dev_info *bdi = wbc->bdi;
const unsigned long start = jiffies; /* livelock avoidance */
spin_lock(&inode_lock);
- if (!wbc->for_kupdate || list_empty(&bdi->b_io))
- queue_io(bdi, wbc->older_than_this);
+ if (!wbc->for_kupdate || list_empty(&wb->b_io))
+ queue_io(wb, wbc->older_than_this);
- while (!list_empty(&bdi->b_io)) {
- struct inode *inode = list_entry(bdi->b_io.prev,
+ while (!list_empty(&wb->b_io)) {
+ struct inode *inode = list_entry(wb->b_io.prev,
struct inode, i_list);
long pages_skipped;
@@ -636,7 +663,7 @@ void generic_sync_bdi_inodes(struct super_block *sb,
continue;
}
- if (!bdi_cap_writeback_dirty(bdi)) {
+ if (!bdi_cap_writeback_dirty(wb->bdi)) {
redirty_tail(inode);
if (is_blkdev_sb) {
/*
@@ -658,7 +685,7 @@ void generic_sync_bdi_inodes(struct super_block *sb,
continue;
}
- if (wbc->nonblocking && bdi_write_congested(bdi)) {
+ if (wbc->nonblocking && bdi_write_congested(wb->bdi)) {
wbc->encountered_congestion = 1;
if (!is_blkdev_sb)
break; /* Skip a congested fs */
@@ -692,7 +719,7 @@ void generic_sync_bdi_inodes(struct super_block *sb,
wbc->more_io = 1;
break;
}
- if (!list_empty(&bdi->b_more_io))
+ if (!list_empty(&wb->b_more_io))
wbc->more_io = 1;
}
@@ -700,6 +727,14 @@ void generic_sync_bdi_inodes(struct super_block *sb,
/* Leave any unwritten inodes on b_io */
}
+void generic_sync_bdi_inodes(struct super_block *sb,
+ struct writeback_control *wbc)
+{
+ struct backing_dev_info *bdi = wbc->bdi;
+
+ generic_sync_wb_inodes(&bdi->wb, sb, wbc);
+}
+
/*
* Write out a superblock's list of dirty inodes. A wait will be performed
* upon no inodes, all inodes or the final one, depending upon sync_mode.
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index f164925..77dc62c 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -24,8 +24,8 @@ struct dentry;
* Bits in backing_dev_info.state
*/
enum bdi_state {
- BDI_pdflush, /* A pdflush thread is working this device */
BDI_pending, /* On its way to being activated */
+ BDI_wb_alloc, /* Default embedded wb allocated */
BDI_async_congested, /* The async (write) queue is getting full */
BDI_sync_congested, /* The sync queue is getting full */
BDI_unused, /* Available bits start here */
@@ -41,15 +41,23 @@ enum bdi_stat_item {
#define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
-struct bdi_writeback_arg {
- unsigned long nr_pages;
- struct super_block *sb;
+struct bdi_writeback {
+ struct backing_dev_info *bdi; /* our parent bdi */
+ unsigned int nr;
+
+ struct task_struct *task; /* writeback task */
+ wait_queue_head_t wait;
+ struct list_head b_dirty; /* dirty inodes */
+ struct list_head b_io; /* parked for writeback */
+ struct list_head b_more_io; /* parked for more writeback */
+
+ unsigned long nr_pages;
+ struct super_block *sb;
enum writeback_sync_modes sync_mode;
};
struct backing_dev_info {
struct list_head bdi_list;
-
unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
unsigned long state; /* Always use atomic bitops on this */
unsigned int capabilities; /* Device capabilities */
@@ -66,14 +74,11 @@ struct backing_dev_info {
unsigned int min_ratio;
unsigned int max_ratio, max_prop_frac;
- struct device *dev;
+ struct bdi_writeback wb; /* default writeback info for this bdi */
+ unsigned long wb_active; /* bitmap of active tasks */
+ unsigned long wb_mask; /* number of registered tasks */
- struct task_struct *task; /* writeback task */
- wait_queue_head_t wait;
- struct bdi_writeback_arg wb_arg; /* protected by BDI_pdflush */
- struct list_head b_dirty; /* dirty inodes */
- struct list_head b_io; /* parked for writeback */
- struct list_head b_more_io; /* parked for more writeback */
+ struct device *dev;
#ifdef CONFIG_DEBUG_FS
struct dentry *debug_dir;
@@ -90,19 +95,20 @@ int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
void bdi_unregister(struct backing_dev_info *bdi);
int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
long nr_pages, enum writeback_sync_modes sync_mode);
-int bdi_writeback_task(struct backing_dev_info *bdi);
+int bdi_writeback_task(struct bdi_writeback *wb);
void bdi_writeback_all(struct super_block *sb, long nr_pages,
enum writeback_sync_modes sync_mode);
void bdi_add_default_flusher_task(struct backing_dev_info *bdi);
+int bdi_has_dirty_io(struct backing_dev_info *bdi);
extern struct mutex bdi_lock;
extern struct list_head bdi_list;
-static inline int bdi_has_dirty_io(struct backing_dev_info *bdi)
+static inline int wb_has_dirty_io(struct bdi_writeback *wb)
{
- return !list_empty(&bdi->b_dirty) ||
- !list_empty(&bdi->b_io) ||
- !list_empty(&bdi->b_more_io);
+ return !list_empty(&wb->b_dirty) ||
+ !list_empty(&wb->b_io) ||
+ !list_empty(&wb->b_more_io);
}
static inline void __add_bdi_stat(struct backing_dev_info *bdi,
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 57c8487..df90b0e 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -199,17 +199,59 @@ static int __init default_bdi_init(void)
}
subsys_initcall(default_bdi_init);
+static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
+{
+ memset(wb, 0, sizeof(*wb));
+
+ wb->bdi = bdi;
+ init_waitqueue_head(&wb->wait);
+ INIT_LIST_HEAD(&wb->b_dirty);
+ INIT_LIST_HEAD(&wb->b_io);
+ INIT_LIST_HEAD(&wb->b_more_io);
+}
+
+static void bdi_flush_io(struct backing_dev_info *bdi)
+{
+ struct writeback_control wbc = {
+ .bdi = bdi,
+ .sync_mode = WB_SYNC_NONE,
+ .older_than_this = NULL,
+ .range_cyclic = 1,
+ .nr_to_write = 1024,
+ };
+
+ generic_sync_bdi_inodes(NULL, &wbc);
+}
+
+static int wb_assign_nr(struct backing_dev_info *bdi, struct bdi_writeback *wb)
+{
+ set_bit(0, &bdi->wb_mask);
+ wb->nr = 0;
+ return 0;
+}
+
+static void bdi_put_wb(struct backing_dev_info *bdi, struct bdi_writeback *wb)
+{
+ clear_bit(wb->nr, &bdi->wb_mask);
+ clear_bit(BDI_wb_alloc, &bdi->state);
+}
+
+static struct bdi_writeback *bdi_new_wb(struct backing_dev_info *bdi)
+{
+ struct bdi_writeback *wb;
+
+ set_bit(BDI_wb_alloc, &bdi->state);
+ wb = &bdi->wb;
+ wb_assign_nr(bdi, wb);
+ return wb;
+}
+
static int bdi_start_fn(void *ptr)
{
- struct backing_dev_info *bdi = ptr;
+ struct bdi_writeback *wb = ptr;
+ struct backing_dev_info *bdi = wb->bdi;
struct task_struct *tsk = current;
-
- /*
- * Add us to the active bdi_list
- */
- mutex_lock(&bdi_lock);
- list_add(&bdi->bdi_list, &bdi_list);
- mutex_unlock(&bdi_lock);
+ int ret;
tsk->flags |= PF_FLUSHER | PF_SWAPWRITE;
set_freezable();
@@ -226,21 +268,33 @@ static int bdi_start_fn(void *ptr)
smp_mb__after_clear_bit();
wake_up_bit(&bdi->state, BDI_pending);
- return bdi_writeback_task(bdi);
+ ret = bdi_writeback_task(wb);
+
+ bdi_put_wb(bdi, wb);
+ return ret;
+}
+
+int bdi_has_dirty_io(struct backing_dev_info *bdi)
+{
+ return wb_has_dirty_io(&bdi->wb);
}
static int bdi_forker_task(void *ptr)
{
- struct backing_dev_info *me = ptr;
+ struct bdi_writeback *me = ptr;
DEFINE_WAIT(wait);
for (;;) {
struct backing_dev_info *bdi, *tmp;
+ struct bdi_writeback *wb;
/*
* Should never trigger on the default bdi
*/
- WARN_ON(bdi_has_dirty_io(me));
+ if (wb_has_dirty_io(me)) {
+ bdi_flush_io(me->bdi);
+ WARN_ON(1);
+ }
prepare_to_wait(&me->wait, &wait, TASK_INTERRUPTIBLE);
@@ -251,7 +305,7 @@ static int bdi_forker_task(void *ptr)
* a thread registered. If so, set that up.
*/
list_for_each_entry_safe(bdi, tmp, &bdi_list, bdi_list) {
- if (bdi->task || !bdi_has_dirty_io(bdi))
+ if (bdi->wb.task || !bdi_has_dirty_io(bdi))
continue;
bdi_add_default_flusher_task(bdi);
@@ -272,24 +326,22 @@ static int bdi_forker_task(void *ptr)
list_del_init(&bdi->bdi_list);
mutex_unlock(&bdi_lock);
- BUG_ON(bdi->task);
+ wb = bdi_new_wb(bdi);
+ if (!wb)
+ goto readd_flush;
- bdi->task = kthread_run(bdi_start_fn, bdi, "bdi-%s",
+ wb->task = kthread_run(bdi_start_fn, wb, "bdi-%s",
dev_name(bdi->dev));
+
/*
* If task creation fails, then readd the bdi to
* the pending list and force writeout of the bdi
* from this forker thread. That will free some memory
* and we can try again.
*/
- if (!bdi->task) {
- struct writeback_control wbc = {
- .bdi = bdi,
- .sync_mode = WB_SYNC_NONE,
- .older_than_this = NULL,
- .range_cyclic = 1,
- };
-
+ if (!wb->task) {
+ bdi_put_wb(bdi, wb);
+readd_flush:
/*
* Add this 'bdi' to the back, so we get
* a chance to flush other bdi's to free
@@ -299,8 +351,7 @@ static int bdi_forker_task(void *ptr)
list_add_tail(&bdi->bdi_list, &bdi_pending_list);
mutex_unlock(&bdi_lock);
- wbc.nr_to_write = 1024;
- generic_sync_bdi_inodes(NULL, &wbc);
+ bdi_flush_io(bdi);
}
}
@@ -308,8 +359,18 @@ static int bdi_forker_task(void *ptr)
return 0;
}
+/*
+ * Add a new flusher task that gets created for any bdi
+ * that has dirty data pending writeout
+ */
void bdi_add_default_flusher_task(struct backing_dev_info *bdi)
{
+ if (!bdi_cap_writeback_dirty(bdi))
+ return;
+
+ /*
+ * Someone already marked this pending for task creation
+ */
if (test_and_set_bit(BDI_pending, &bdi->state))
return;
@@ -317,7 +378,7 @@ void bdi_add_default_flusher_task(struct backing_dev_info *bdi)
list_move_tail(&bdi->bdi_list, &bdi_pending_list);
mutex_unlock(&bdi_lock);
- wake_up(&default_backing_dev_info.wait);
+ wake_up(&default_backing_dev_info.wb.wait);
}
int bdi_register(struct backing_dev_info *bdi, struct device *parent,
@@ -350,13 +411,23 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent,
* on-demand when they need it.
*/
if (bdi_cap_flush_forker(bdi)) {
- bdi->task = kthread_run(bdi_forker_task, bdi, "bdi-%s",
+ struct bdi_writeback *wb;
+
+ wb = bdi_new_wb(bdi);
+ if (!wb) {
+ ret = -ENOMEM;
+ goto remove_err;
+ }
+
+ wb->task = kthread_run(bdi_forker_task, wb, "bdi-%s",
dev_name(dev));
- if (!bdi->task) {
+ if (!wb->task) {
+ bdi_put_wb(bdi, wb);
+ ret = -ENOMEM;
+remove_err:
mutex_lock(&bdi_lock);
list_del(&bdi->bdi_list);
mutex_unlock(&bdi_lock);
- ret = -ENOMEM;
goto exit;
}
}
@@ -379,28 +450,39 @@ static int sched_wait(void *word)
return 0;
}
+/*
+ * Remove bdi from global list and shutdown any threads we have running
+ */
static void bdi_wb_shutdown(struct backing_dev_info *bdi)
{
+ if (!bdi_cap_writeback_dirty(bdi))
+ return;
+
/*
* If setup is pending, wait for that to complete first
+ * Make sure nobody finds us on the bdi_list anymore
*/
wait_on_bit(&bdi->state, BDI_pending, sched_wait, TASK_UNINTERRUPTIBLE);
+ /*
+ * Make sure nobody finds us on the bdi_list anymore
+ */
mutex_lock(&bdi_lock);
list_del(&bdi->bdi_list);
mutex_unlock(&bdi_lock);
+
+ /*
+ * Finally, kill the kernel thread
+ */
+ kthread_stop(bdi->wb.task);
}
void bdi_unregister(struct backing_dev_info *bdi)
{
if (bdi->dev) {
- if (!bdi_cap_flush_forker(bdi)) {
+ if (!bdi_cap_flush_forker(bdi))
bdi_wb_shutdown(bdi);
- if (bdi->task) {
- kthread_stop(bdi->task);
- bdi->task = NULL;
- }
- }
+
bdi_debug_unregister(bdi);
device_unregister(bdi->dev);
bdi->dev = NULL;
@@ -417,11 +499,10 @@ int bdi_init(struct backing_dev_info *bdi)
bdi->min_ratio = 0;
bdi->max_ratio = 100;
bdi->max_prop_frac = PROP_FRAC_BASE;
- init_waitqueue_head(&bdi->wait);
INIT_LIST_HEAD(&bdi->bdi_list);
- INIT_LIST_HEAD(&bdi->b_io);
- INIT_LIST_HEAD(&bdi->b_dirty);
- INIT_LIST_HEAD(&bdi->b_more_io);
+ bdi->wb_mask = bdi->wb_active = 0;
+
+ bdi_wb_init(&bdi->wb, bdi);
for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
err = percpu_counter_init(&bdi->bdi_stat[i], 0);
@@ -446,9 +527,7 @@ void bdi_destroy(struct backing_dev_info *bdi)
{
int i;
- WARN_ON(!list_empty(&bdi->b_dirty));
- WARN_ON(!list_empty(&bdi->b_io));
- WARN_ON(!list_empty(&bdi->b_more_io));
+ WARN_ON(bdi_has_dirty_io(bdi));
bdi_unregister(bdi);
--
1.6.3.rc0.1.gf800
^ permalink raw reply related [flat|nested] 27+ messages in thread
* [PATCH 07/12] writeback: support > 1 flusher thread per bdi
2009-05-25 7:34 [PATCH 0/12] Per-bdi writeback flusher threads #5 Jens Axboe
` (5 preceding siblings ...)
2009-05-25 7:34 ` [PATCH 06/12] writeback: separate the flushing state/task from the bdi Jens Axboe
@ 2009-05-25 7:34 ` Jens Axboe
2009-05-25 7:34 ` [PATCH 08/12] writeback: include default_backing_dev_info in writeback Jens Axboe
` (4 subsequent siblings)
11 siblings, 0 replies; 27+ messages in thread
From: Jens Axboe @ 2009-05-25 7:34 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, hch, akpm, jack, yanmin_zhang, Jens Axboe
Build on the bdi_writeback support by allowing registration of
more than 1 flusher thread. File systems can call bdi_add_flusher_task(bdi)
to add more flusher threads to the device. If they do so, they must also
provide a super_operations function to return the suitable bdi_writeback
struct from any given inode.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
fs/fs-writeback.c | 346 +++++++++++++++++++++++++++++++++----------
include/linux/backing-dev.h | 32 ++++-
include/linux/fs.h | 3 +
mm/backing-dev.c | 244 ++++++++++++++++++++++++------
mm/page-writeback.c | 4 +-
5 files changed, 495 insertions(+), 134 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 7a9f0b0..563860c 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -34,86 +34,196 @@
*/
int nr_pdflush_threads;
-/**
- * writeback_acquire - attempt to get exclusive writeback access to a device
- * @bdi: the device's backing_dev_info structure
- *
- * It is a waste of resources to have more than one pdflush thread blocked on
- * a single request queue. Exclusion at the request_queue level is obtained
- * via a flag in the request_queue's backing_dev_info.state.
- *
- * Non-request_queue-backed address_spaces will share default_backing_dev_info,
- * unless they implement their own. Which is somewhat inefficient, as this
- * may prevent concurrent writeback against multiple devices.
+static void generic_sync_wb_inodes(struct bdi_writeback *wb,
+ struct super_block *sb,
+ struct writeback_control *wbc);
+
+/*
+ * Work items for the bdi_writeback threads
*/
-static int writeback_acquire(struct bdi_writeback *wb)
+struct bdi_work {
+ struct list_head list;
+ struct rcu_head rcu_head;
+
+ unsigned long seen;
+ atomic_t pending;
+
+ unsigned long sb_data;
+ unsigned long nr_pages;
+ enum writeback_sync_modes sync_mode;
+
+ unsigned long state;
+};
+
+static struct super_block *bdi_work_sb(struct bdi_work *work)
{
- struct backing_dev_info *bdi = wb->bdi;
+ return (struct super_block *) (work->sb_data & ~1UL);
+}
+
+static inline bool bdi_work_on_stack(struct bdi_work *work)
+{
+ return work->sb_data & 1UL;
+}
+
+static inline void bdi_work_init(struct bdi_work *work, struct super_block *sb,
+ unsigned long nr_pages,
+ enum writeback_sync_modes sync_mode)
+{
+ INIT_RCU_HEAD(&work->rcu_head);
+ work->sb_data = (unsigned long) sb;
+ work->nr_pages = nr_pages;
+ work->sync_mode = sync_mode;
+ work->state = 0;
+}
- return !test_and_set_bit(wb->nr, &bdi->wb_active);
+static inline void bdi_work_init_on_stack(struct bdi_work *work,
+ struct super_block *sb,
+ unsigned long nr_pages,
+ enum writeback_sync_modes sync_mode)
+{
+ bdi_work_init(work, sb, nr_pages, sync_mode);
+ set_bit(0, &work->state);
+ work->sb_data |= 1UL;
}
/**
* writeback_in_progress - determine whether there is writeback in progress
* @bdi: the device's backing_dev_info structure.
*
- * Determine whether there is writeback in progress against a backing device.
+ * Determine whether there is writeback waiting to be handled against a
+ * backing device.
*/
int writeback_in_progress(struct backing_dev_info *bdi)
{
- return bdi->wb_active != 0;
+ return !list_empty(&bdi->work_list);
}
-/**
- * writeback_release - relinquish exclusive writeback access against a device.
- * @bdi: the device's backing_dev_info structure
- */
-static void writeback_release(struct bdi_writeback *wb)
+static void bdi_work_free(struct rcu_head *head)
{
- struct backing_dev_info *bdi = wb->bdi;
+ struct bdi_work *work = container_of(head, struct bdi_work, rcu_head);
+
+ if (!bdi_work_on_stack(work))
+ kfree(work);
+ else {
+ clear_bit(0, &work->state);
+ smp_mb__after_clear_bit();
+ wake_up_bit(&work->state, 0);
+ }
+}
+
+static void wb_clear_pending(struct bdi_writeback *wb, struct bdi_work *work)
+{
+ /*
+ * The caller has retrieved the work arguments from this work,
+ * drop our reference. If this is the last ref, delete and free it
+ */
+ if (atomic_dec_and_test(&work->pending)) {
+ struct backing_dev_info *bdi = wb->bdi;
- wb->nr_pages = 0;
- wb->sb = NULL;
- clear_bit(wb->nr, &bdi->wb_active);
+ spin_lock(&bdi->wb_lock);
+ list_del_rcu(&work->list);
+ spin_unlock(&bdi->wb_lock);
+
+ call_rcu(&work->rcu_head, bdi_work_free);
+ }
}
-static void wb_start_writeback(struct bdi_writeback *wb, struct super_block *sb,
- long nr_pages,
- enum writeback_sync_modes sync_mode)
+static void wb_start_writeback(struct bdi_writeback *wb, struct bdi_work *work)
{
- if (!wb_has_dirty_io(wb))
- return;
+ /*
+ * If we failed allocating the bdi work item, wake up the wb thread
+ * always. As a safety precaution, it'll flush out everything
+ */
+ if (!wb_has_dirty_io(wb) && work)
+ wb_clear_pending(wb, work);
+ else
+ wake_up(&wb->wait);
+}
- if (writeback_acquire(wb)) {
- wb->nr_pages = nr_pages;
- wb->sb = sb;
- wb->sync_mode = sync_mode;
+/*
+ * Add work to bdi work list.
+ */
+static int bdi_queue_writeback(struct backing_dev_info *bdi,
+ struct bdi_work *work)
+{
+ if (work) {
+ work->seen = bdi->wb_mask;
+ atomic_set(&work->pending, bdi->wb_cnt);
/*
- * make above store seen before the task is woken
+ * Make sure stores are seen before it appears on the list
*/
smp_mb();
- wake_up(&wb->wait);
+
+ spin_lock(&bdi->wb_lock);
+ list_add_tail_rcu(&work->list, &bdi->work_list);
+ spin_unlock(&bdi->wb_lock);
}
-}
-int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
- long nr_pages, enum writeback_sync_modes sync_mode)
-{
/*
* This only happens the first time someone kicks this bdi, so put
* it out-of-line.
*/
- if (unlikely(!bdi->wb.task)) {
+ if (unlikely(list_empty_careful(&bdi->wb_list))) {
+ mutex_lock(&bdi_lock);
bdi_add_default_flusher_task(bdi);
+ mutex_unlock(&bdi_lock);
return 1;
}
- wb_start_writeback(&bdi->wb, sb, nr_pages, sync_mode);
+ if (!bdi_wblist_needs_lock(bdi))
+ wb_start_writeback(&bdi->wb, work);
+ else {
+ struct bdi_writeback *wb;
+ int idx;
+
+ idx = srcu_read_lock(&bdi->srcu);
+
+ list_for_each_entry_rcu(wb, &bdi->wb_list, list)
+ wb_start_writeback(wb, work);
+
+ srcu_read_unlock(&bdi->srcu, idx);
+ }
+
return 0;
}
/*
+ * Used for on-stack allocated work items. The caller needs to wait until
+ * the wb threads have acked the work before it's safe to continue.
+ */
+static void bdi_wait_on_work_start(struct bdi_work *work)
+{
+ wait_on_bit(&work->state, 0, bdi_sched_wait, TASK_UNINTERRUPTIBLE);
+}
+
+int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
+ long nr_pages, enum writeback_sync_modes sync_mode)
+{
+ struct bdi_work work_stack, *work;
+ int ret;
+
+ work = kmalloc(sizeof(*work), GFP_ATOMIC);
+ if (work)
+ bdi_work_init(work, sb, nr_pages, sync_mode);
+ else {
+ work = &work_stack;
+ bdi_work_init_on_stack(work, sb, nr_pages, sync_mode);
+ }
+
+ ret = bdi_queue_writeback(bdi, work);
+
+ /*
+ * If this came from our stack, we need to wait until the wb threads
+ * have noticed this work before we return (and invalidate the stack)
+ */
+ if (work == &work_stack)
+ bdi_wait_on_work_start(work);
+
+ return ret;
+}
+
+/*
* The maximum number of pages to writeout in a single bdi flush/kupdate
* operation. We do this so we don't hold I_SYNC against an inode for
* enormous amounts of time, which would block a userspace task which has
@@ -162,7 +272,7 @@ static void wb_kupdated(struct bdi_writeback *wb)
wbc.more_io = 0;
wbc.encountered_congestion = 0;
wbc.nr_to_write = MAX_WRITEBACK_PAGES;
- generic_sync_bdi_inodes(NULL, &wbc);
+ generic_sync_wb_inodes(wb, NULL, &wbc);
if (wbc.nr_to_write > 0)
break; /* All the old data is written */
nr_to_write -= MAX_WRITEBACK_PAGES;
@@ -179,22 +289,19 @@ static inline bool over_bground_thresh(void)
global_page_state(NR_UNSTABLE_NFS) >= background_thresh);
}
-static void generic_sync_wb_inodes(struct bdi_writeback *wb,
- struct super_block *sb,
- struct writeback_control *wbc);
-
-static void wb_writeback(struct bdi_writeback *wb)
+static void __wb_writeback(struct bdi_writeback *wb, long nr_pages,
+ struct super_block *sb,
+ enum writeback_sync_modes sync_mode)
{
struct writeback_control wbc = {
.bdi = wb->bdi,
- .sync_mode = wb->sync_mode,
+ .sync_mode = sync_mode,
.older_than_this = NULL,
.range_cyclic = 1,
};
- long nr_pages = wb->nr_pages;
for (;;) {
- if (wbc.sync_mode == WB_SYNC_NONE && nr_pages <= 0 &&
+ if (sync_mode == WB_SYNC_NONE && nr_pages <= 0 &&
!over_bground_thresh())
break;
@@ -202,7 +309,7 @@ static void wb_writeback(struct bdi_writeback *wb)
wbc.encountered_congestion = 0;
wbc.nr_to_write = MAX_WRITEBACK_PAGES;
wbc.pages_skipped = 0;
- generic_sync_wb_inodes(wb, wb->sb, &wbc);
+ generic_sync_wb_inodes(wb, sb, &wbc);
nr_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
/*
* If we ran out of stuff to write, bail unless more_io got set
@@ -216,46 +323,91 @@ static void wb_writeback(struct bdi_writeback *wb)
}
/*
+ * Return the next bdi_work struct that hasn't been processed by this
+ * wb thread yet
+ */
+static struct bdi_work *get_next_work_item(struct backing_dev_info *bdi,
+ struct bdi_writeback *wb)
+{
+ struct bdi_work *work, *ret = NULL;
+
+ rcu_read_lock();
+
+ list_for_each_entry_rcu(work, &bdi->work_list, list) {
+ if (!test_and_clear_bit(wb->nr, &work->seen))
+ continue;
+
+ ret = work;
+ break;
+ }
+
+ rcu_read_unlock();
+ return ret;
+}
+
+static void wb_writeback(struct bdi_writeback *wb)
+{
+ struct backing_dev_info *bdi = wb->bdi;
+ struct bdi_work *work;
+
+ while ((work = get_next_work_item(bdi, wb)) != NULL) {
+ struct super_block *sb = bdi_work_sb(work);
+ long nr_pages = work->nr_pages;
+ enum writeback_sync_modes sync_mode = work->sync_mode;
+
+ wb_clear_pending(wb, work);
+ __wb_writeback(wb, nr_pages, sb, sync_mode);
+ }
+}
+
+/*
+ * This will be inlined in bdi_writeback_task() once we get rid of any
+ * dirty inodes on the default_backing_dev_info
+ */
+static void wb_do_writeback(struct bdi_writeback *wb)
+{
+ /*
+ * We get here in two cases:
+ *
+ * schedule_timeout() returned because the dirty writeback
+ * interval has elapsed. If that happens, the work item list
+ * will be empty and we will proceed to do kupdated style writeout.
+ *
+ * Someone called bdi_start_writeback(), which put one/more work
+ * items on the work_list. Process those.
+ */
+ if (list_empty(&wb->bdi->work_list))
+ wb_kupdated(wb);
+ else
+ wb_writeback(wb);
+}
+
+/*
* Handle writeback of dirty data for the device backed by this bdi. Also
* wakes up periodically and does kupdated style flushing.
*/
int bdi_writeback_task(struct bdi_writeback *wb)
{
+ DEFINE_WAIT(wait);
+
while (!kthread_should_stop()) {
unsigned long wait_jiffies;
- DEFINE_WAIT(wait);
+
+ wb_do_writeback(wb);
prepare_to_wait(&wb->wait, &wait, TASK_INTERRUPTIBLE);
wait_jiffies = msecs_to_jiffies(dirty_writeback_interval * 10);
schedule_timeout(wait_jiffies);
try_to_freeze();
-
- /*
- * We get here in two cases:
- *
- * schedule_timeout() returned because the dirty writeback
- * interval has elapsed. If that happens, we will be able
- * to acquire the writeback lock and will proceed to do
- * kupdated style writeout.
- *
- * Someone called bdi_start_writeback(), which will acquire
- * the writeback lock. This means our writeback_acquire()
- * below will fail and we call into bdi_pdflush() for
- * pdflush style writeout.
- *
- */
- if (writeback_acquire(wb))
- wb_kupdated(wb);
- else
- wb_writeback(wb);
-
- writeback_release(wb);
- finish_wait(&wb->wait, &wait);
}
+ finish_wait(&wb->wait, &wait);
return 0;
}
+/*
+ * Do in-line writeback for all backing devices. Expensive!
+ */
void bdi_writeback_all(struct super_block *sb, long nr_pages,
enum writeback_sync_modes sync_mode)
{
@@ -266,18 +418,38 @@ void bdi_writeback_all(struct super_block *sb, long nr_pages,
list_for_each_entry_safe(bdi, tmp, &bdi_list, bdi_list) {
if (!bdi_has_dirty_io(bdi))
continue;
- bdi_start_writeback(bdi, sb, nr_pages, sync_mode);
+
+ if (!bdi_wblist_needs_lock(bdi))
+ __wb_writeback(&bdi->wb, 0, sb, sync_mode);
+ else {
+ struct bdi_writeback *wb;
+ int idx;
+
+ idx = srcu_read_lock(&bdi->srcu);
+
+ list_for_each_entry_rcu(wb, &bdi->wb_list, list)
+ __wb_writeback(&bdi->wb, 0, sb, sync_mode);
+
+ srcu_read_unlock(&bdi->srcu, idx);
+ }
}
mutex_unlock(&bdi_lock);
}
/*
- * We have only a single wb per bdi, so just return that.
+ * If the filesystem didn't provide a way to map an inode to a dedicated
+ * flusher thread, it doesn't support more than 1 thread. So we know it's
+ * the default thread, return that.
*/
static inline struct bdi_writeback *inode_get_wb(struct inode *inode)
{
- return &inode_to_bdi(inode)->wb;
+ const struct super_operations *sop = inode->i_sb->s_op;
+
+ if (!sop->inode_get_wb)
+ return &inode_to_bdi(inode)->wb;
+
+ return sop->inode_get_wb(inode);
}
/**
@@ -731,8 +903,24 @@ void generic_sync_bdi_inodes(struct super_block *sb,
struct writeback_control *wbc)
{
struct backing_dev_info *bdi = wbc->bdi;
+ struct bdi_writeback *wb;
+
+ /*
+ * Common case is just a single wb thread and that is embedded in
+ * the bdi, so it doesn't need locking
+ */
+ if (!bdi_wblist_needs_lock(bdi))
+ generic_sync_wb_inodes(&bdi->wb, sb, wbc);
+ else {
+ int idx;
- generic_sync_wb_inodes(&bdi->wb, sb, wbc);
+ idx = srcu_read_lock(&bdi->srcu);
+
+ list_for_each_entry_rcu(wb, &bdi->wb_list, list)
+ generic_sync_wb_inodes(wb, sb, wbc);
+
+ srcu_read_unlock(&bdi->srcu, idx);
+ }
}
/*
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 77dc62c..72b4797 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -13,6 +13,8 @@
#include <linux/proportions.h>
#include <linux/kernel.h>
#include <linux/fs.h>
+#include <linux/sched.h>
+#include <linux/srcu.h>
#include <linux/writeback.h>
#include <asm/atomic.h>
@@ -26,6 +28,7 @@ struct dentry;
enum bdi_state {
BDI_pending, /* On its way to being activated */
BDI_wb_alloc, /* Default embedded wb allocated */
+ BDI_wblist_lock, /* bdi->wb_list now needs locking */
BDI_async_congested, /* The async (write) queue is getting full */
BDI_sync_congested, /* The sync queue is getting full */
BDI_unused, /* Available bits start here */
@@ -42,6 +45,8 @@ enum bdi_stat_item {
#define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
struct bdi_writeback {
+ struct list_head list; /* hangs off the bdi */
+
struct backing_dev_info *bdi; /* our parent bdi */
unsigned int nr;
@@ -50,13 +55,12 @@ struct bdi_writeback {
struct list_head b_dirty; /* dirty inodes */
struct list_head b_io; /* parked for writeback */
struct list_head b_more_io; /* parked for more writeback */
-
- unsigned long nr_pages;
- struct super_block *sb;
- enum writeback_sync_modes sync_mode;
};
+#define BDI_MAX_FLUSHERS 32
+
struct backing_dev_info {
+ struct srcu_struct srcu; /* for wb_list read side protection */
struct list_head bdi_list;
unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
unsigned long state; /* Always use atomic bitops on this */
@@ -75,8 +79,12 @@ struct backing_dev_info {
unsigned int max_ratio, max_prop_frac;
struct bdi_writeback wb; /* default writeback info for this bdi */
- unsigned long wb_active; /* bitmap of active tasks */
- unsigned long wb_mask; /* number of registered tasks */
+ spinlock_t wb_lock; /* protects update side of wb_list */
+ struct list_head wb_list; /* the flusher threads hanging off this bdi */
+ unsigned long wb_mask; /* bitmask of registered tasks */
+ unsigned int wb_cnt; /* number of registered tasks */
+
+ struct list_head work_list;
struct device *dev;
@@ -99,11 +107,17 @@ int bdi_writeback_task(struct bdi_writeback *wb);
void bdi_writeback_all(struct super_block *sb, long nr_pages,
enum writeback_sync_modes sync_mode);
void bdi_add_default_flusher_task(struct backing_dev_info *bdi);
+void bdi_add_flusher_task(struct backing_dev_info *bdi);
int bdi_has_dirty_io(struct backing_dev_info *bdi);
extern struct mutex bdi_lock;
extern struct list_head bdi_list;
+static inline int bdi_wblist_needs_lock(struct backing_dev_info *bdi)
+{
+ return test_bit(BDI_wblist_lock, &bdi->state);
+}
+
static inline int wb_has_dirty_io(struct bdi_writeback *wb)
{
return !list_empty(&wb->b_dirty) ||
@@ -316,4 +330,10 @@ static inline bool mapping_cap_swap_backed(struct address_space *mapping)
return bdi_cap_swap_backed(mapping->backing_dev_info);
}
+static inline int bdi_sched_wait(void *word)
+{
+ schedule();
+ return 0;
+}
+
#endif /* _LINUX_BACKING_DEV_H */
diff --git a/include/linux/fs.h b/include/linux/fs.h
index ecdc544..d3bda5d 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1550,11 +1550,14 @@ extern ssize_t vfs_readv(struct file *, const struct iovec __user *,
extern ssize_t vfs_writev(struct file *, const struct iovec __user *,
unsigned long, loff_t *);
+struct bdi_writeback;
+
struct super_operations {
struct inode *(*alloc_inode)(struct super_block *sb);
void (*destroy_inode)(struct inode *);
void (*dirty_inode) (struct inode *);
+ struct bdi_writeback *(*inode_get_wb) (struct inode *);
int (*write_inode) (struct inode *, int);
void (*drop_inode) (struct inode *);
void (*delete_inode) (struct inode *);
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index df90b0e..3e74041 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -199,7 +199,42 @@ static int __init default_bdi_init(void)
}
subsys_initcall(default_bdi_init);
-static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
+static int wb_assign_nr(struct backing_dev_info *bdi, struct bdi_writeback *wb)
+{
+ unsigned long mask = BDI_MAX_FLUSHERS - 1;
+ unsigned int nr;
+
+ do {
+ if ((bdi->wb_mask & mask) == mask)
+ return 1;
+
+ nr = find_first_zero_bit(&bdi->wb_mask, BDI_MAX_FLUSHERS);
+ } while (test_and_set_bit(nr, &bdi->wb_mask));
+
+ wb->nr = nr;
+
+ spin_lock(&bdi->wb_lock);
+ bdi->wb_cnt++;
+ spin_unlock(&bdi->wb_lock);
+
+ return 0;
+}
+
+static void bdi_put_wb(struct backing_dev_info *bdi, struct bdi_writeback *wb)
+{
+ clear_bit(wb->nr, &bdi->wb_mask);
+
+ if (wb == &bdi->wb)
+ clear_bit(BDI_wb_alloc, &bdi->state);
+ else
+ kfree(wb);
+
+ spin_lock(&bdi->wb_lock);
+ bdi->wb_cnt--;
+ spin_unlock(&bdi->wb_lock);
+}
+
+static int bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
{
memset(wb, 0, sizeof(*wb));
@@ -208,6 +243,30 @@ static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
INIT_LIST_HEAD(&wb->b_dirty);
INIT_LIST_HEAD(&wb->b_io);
INIT_LIST_HEAD(&wb->b_more_io);
+
+ return wb_assign_nr(bdi, wb);
+}
+
+static struct bdi_writeback *bdi_new_wb(struct backing_dev_info *bdi)
+{
+ struct bdi_writeback *wb;
+
+ /*
+ * Default bdi->wb is already assigned, so just return it
+ */
+ if (!test_and_set_bit(BDI_wb_alloc, &bdi->state))
+ wb = &bdi->wb;
+ else {
+ wb = kmalloc(sizeof(struct bdi_writeback), GFP_KERNEL);
+ if (wb) {
+ if (bdi_wb_init(wb, bdi)) {
+ kfree(wb);
+ wb = NULL;
+ }
+ }
+ }
+
+ return wb;
}
static void bdi_flush_io(struct backing_dev_info *bdi)
@@ -223,35 +282,26 @@ static void bdi_flush_io(struct backing_dev_info *bdi)
generic_sync_bdi_inodes(NULL, &wbc);
}
-static int wb_assign_nr(struct backing_dev_info *bdi, struct bdi_writeback *wb)
+static void bdi_task_init(struct backing_dev_info *bdi,
+ struct bdi_writeback *wb)
{
- set_bit(0, &bdi->wb_mask);
- wb->nr = 0;
- return 0;
-}
-
-static void bdi_put_wb(struct backing_dev_info *bdi, struct bdi_writeback *wb)
-{
- clear_bit(wb->nr, &bdi->wb_mask);
- clear_bit(BDI_wb_alloc, &bdi->state);
-}
+ struct task_struct *tsk = current;
+ int was_empty;
-static struct bdi_writeback *bdi_new_wb(struct backing_dev_info *bdi)
-{
- struct bdi_writeback *wb;
+ /*
+ * Add us to the active bdi_list. If we are adding threads beyond
+ * the default embedded bdi_writeback, then we need to start using
+ * proper locking. Check the list for empty first, then set the
+ * BDI_wblist_lock flag if there's > 1 entry on the list now
+ */
+ spin_lock(&bdi->wb_lock);
- set_bit(BDI_wb_alloc, &bdi->state);
- wb = &bdi->wb;
- wb_assign_nr(bdi, wb);
- return wb;
-}
+ was_empty = list_empty(&bdi->wb_list);
+ list_add_tail_rcu(&wb->list, &bdi->wb_list);
+ if (!was_empty)
+ set_bit(BDI_wblist_lock, &bdi->state);
-static int bdi_start_fn(void *ptr)
-{
- struct bdi_writeback *wb = ptr;
- struct backing_dev_info *bdi = wb->bdi;
- struct task_struct *tsk = current;
- int ret;
+ spin_unlock(&bdi->wb_lock);
tsk->flags |= PF_FLUSHER | PF_SWAPWRITE;
set_freezable();
@@ -260,6 +310,15 @@ static int bdi_start_fn(void *ptr)
* Our parent may run at a different priority, just set us to normal
*/
set_user_nice(tsk, 0);
+}
+
+static int bdi_start_fn(void *ptr)
+{
+ struct bdi_writeback *wb = ptr;
+ struct backing_dev_info *bdi = wb->bdi;
+ int ret;
+
+ bdi_task_init(bdi, wb);
/*
* Clear pending bit and wakeup anybody waiting to tear us down
@@ -268,15 +327,53 @@ static int bdi_start_fn(void *ptr)
smp_mb__after_clear_bit();
wake_up_bit(&bdi->state, BDI_pending);
+ /*
+ * Make us discoverable on the bdi_list again
+ */
+ mutex_lock(&bdi_lock);
+ list_add_tail(&bdi->bdi_list, &bdi_list);
+ mutex_unlock(&bdi_lock);
+
ret = bdi_writeback_task(wb);
+ /*
+ * Remove us from the list
+ */
+ spin_lock(&bdi->wb_lock);
+ list_del_rcu(&wb->list);
+ spin_unlock(&bdi->wb_lock);
+
+ /*
+ * wait for rcu grace period to end, so we can free wb
+ */
+ synchronize_srcu(&bdi->srcu);
+
bdi_put_wb(bdi, wb);
return ret;
}
int bdi_has_dirty_io(struct backing_dev_info *bdi)
{
- return wb_has_dirty_io(&bdi->wb);
+ struct bdi_writeback *wb;
+ int ret = 0;
+
+ if (!bdi_wblist_needs_lock(bdi))
+ ret = wb_has_dirty_io(&bdi->wb);
+ else {
+ int idx;
+
+ idx = srcu_read_lock(&bdi->srcu);
+
+ list_for_each_entry_rcu(wb, &bdi->wb_list, list) {
+ ret = wb_has_dirty_io(wb);
+ if (ret)
+ break;
+ }
+
+ srcu_read_unlock(&bdi->srcu, idx);
+ }
+
+ return ret;
}
static int bdi_forker_task(void *ptr)
@@ -284,6 +381,8 @@ static int bdi_forker_task(void *ptr)
struct bdi_writeback *me = ptr;
DEFINE_WAIT(wait);
+ bdi_task_init(me->bdi, me);
+
for (;;) {
struct backing_dev_info *bdi, *tmp;
struct bdi_writeback *wb;
@@ -360,26 +459,69 @@ readd_flush:
}
/*
- * Add a new flusher task that gets created for any bdi
- * that has dirty data pending writeout
+ * bdi_lock held on entry
*/
-void bdi_add_default_flusher_task(struct backing_dev_info *bdi)
+static void bdi_add_one_flusher_task(struct backing_dev_info *bdi,
+ int(*func)(struct backing_dev_info *))
{
if (!bdi_cap_writeback_dirty(bdi))
return;
/*
- * Someone already marked this pending for task creation
+ * Check with the helper whether to proceed adding a task. Will only
+ * abort if we two or more simultanous calls to
+ * bdi_add_default_flusher_task() occured, further additions will block
+ * waiting for previous additions to finish.
*/
- if (test_and_set_bit(BDI_pending, &bdi->state))
- return;
+ if (!func(bdi)) {
+ list_move_tail(&bdi->bdi_list, &bdi_pending_list);
- mutex_lock(&bdi_lock);
- list_move_tail(&bdi->bdi_list, &bdi_pending_list);
+ /*
+ * We are now on the pending list, wake up bdi_forker_task()
+ * to finish the job and add us back to the active bdi_list
+ */
+ wake_up(&default_backing_dev_info.wb.wait);
+ }
+}
+
+static int flusher_add_helper_block(struct backing_dev_info *bdi)
+{
mutex_unlock(&bdi_lock);
+ wait_on_bit_lock(&bdi->state, BDI_pending, bdi_sched_wait,
+ TASK_UNINTERRUPTIBLE);
+ mutex_lock(&bdi_lock);
+ return 0;
+}
+
+static int flusher_add_helper_test(struct backing_dev_info *bdi)
+{
+ return test_and_set_bit(BDI_pending, &bdi->state);
+}
+
+/*
+ * Add the default flusher task that gets created for any bdi
+ * that has dirty data pending writeout
+ */
+void bdi_add_default_flusher_task(struct backing_dev_info *bdi)
+{
+ bdi_add_one_flusher_task(bdi, flusher_add_helper_test);
+}
- wake_up(&default_backing_dev_info.wb.wait);
+/**
+ * bdi_add_flusher_task - add one more flusher task to this @bdi
+ * @bdi: the bdi
+ *
+ * Add an additional flusher task to this @bdi. Will block waiting on
+ * previous additions, if any.
+ *
+ */
+void bdi_add_flusher_task(struct backing_dev_info *bdi)
+{
+ mutex_lock(&bdi_lock);
+ bdi_add_one_flusher_task(bdi, flusher_add_helper_block);
+ mutex_unlock(&bdi_lock);
}
+EXPORT_SYMBOL(bdi_add_flusher_task);
int bdi_register(struct backing_dev_info *bdi, struct device *parent,
const char *fmt, ...)
@@ -444,17 +586,13 @@ int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)
}
EXPORT_SYMBOL(bdi_register_dev);
-static int sched_wait(void *word)
-{
- schedule();
- return 0;
-}
-
/*
* Remove bdi from global list and shutdown any threads we have running
*/
static void bdi_wb_shutdown(struct backing_dev_info *bdi)
{
+ struct bdi_writeback *wb;
+
if (!bdi_cap_writeback_dirty(bdi))
return;
@@ -462,7 +600,8 @@ static void bdi_wb_shutdown(struct backing_dev_info *bdi)
* If setup is pending, wait for that to complete first
* Make sure nobody finds us on the bdi_list anymore
*/
- wait_on_bit(&bdi->state, BDI_pending, sched_wait, TASK_UNINTERRUPTIBLE);
+ wait_on_bit(&bdi->state, BDI_pending, bdi_sched_wait,
+ TASK_UNINTERRUPTIBLE);
/*
* Make sure nobody finds us on the bdi_list anymore
@@ -472,9 +611,11 @@ static void bdi_wb_shutdown(struct backing_dev_info *bdi)
mutex_unlock(&bdi_lock);
/*
- * Finally, kill the kernel thread
+ * Finally, kill the kernel threads. We don't need to be RCU
+ * safe anymore, since the bdi is gone from visibility.
*/
- kthread_stop(bdi->wb.task);
+ list_for_each_entry(wb, &bdi->wb_list, list)
+ kthread_stop(wb->task);
}
void bdi_unregister(struct backing_dev_info *bdi)
@@ -499,8 +640,12 @@ int bdi_init(struct backing_dev_info *bdi)
bdi->min_ratio = 0;
bdi->max_ratio = 100;
bdi->max_prop_frac = PROP_FRAC_BASE;
+ spin_lock_init(&bdi->wb_lock);
+ bdi->wb_mask = 0;
+ bdi->wb_cnt = 0;
INIT_LIST_HEAD(&bdi->bdi_list);
- bdi->wb_mask = bdi->wb_active = 0;
+ INIT_LIST_HEAD(&bdi->wb_list);
+ INIT_LIST_HEAD(&bdi->work_list);
bdi_wb_init(&bdi->wb, bdi);
@@ -510,10 +655,15 @@ int bdi_init(struct backing_dev_info *bdi)
goto err;
}
+ err = init_srcu_struct(&bdi->srcu);
+ if (err)
+ goto err;
+
bdi->dirty_exceeded = 0;
err = prop_local_init_percpu(&bdi->completions);
if (err) {
+ cleanup_srcu_struct(&bdi->srcu);
err:
while (i--)
percpu_counter_destroy(&bdi->bdi_stat[i]);
@@ -531,6 +681,8 @@ void bdi_destroy(struct backing_dev_info *bdi)
bdi_unregister(bdi);
+ cleanup_srcu_struct(&bdi->srcu);
+
for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
percpu_counter_destroy(&bdi->bdi_stat[i]);
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 54a4a65..7dd7de7 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -665,8 +665,7 @@ void throttle_vm_writeout(gfp_t gfp_mask)
/*
* Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back
- * the whole world. Returns 0 if a pdflush thread was dispatched. Returns
- * -1 if all pdflush threads were busy.
+ * the whole world.
*/
void wakeup_flusher_threads(long nr_pages)
{
@@ -674,7 +673,6 @@ void wakeup_flusher_threads(long nr_pages)
nr_pages = global_page_state(NR_FILE_DIRTY) +
global_page_state(NR_UNSTABLE_NFS);
bdi_writeback_all(NULL, nr_pages, WB_SYNC_NONE);
- return;
}
static void laptop_timer_fn(unsigned long unused);
--
1.6.3.rc0.1.gf800
^ permalink raw reply related [flat|nested] 27+ messages in thread
* [PATCH 08/12] writeback: include default_backing_dev_info in writeback
2009-05-25 7:34 [PATCH 0/12] Per-bdi writeback flusher threads #5 Jens Axboe
` (6 preceding siblings ...)
2009-05-25 7:34 ` [PATCH 07/12] writeback: support > 1 flusher thread per bdi Jens Axboe
@ 2009-05-25 7:34 ` Jens Axboe
2009-05-25 7:34 ` [PATCH 09/12] writeback: allow sleepy exit of default writeback task Jens Axboe
` (3 subsequent siblings)
11 siblings, 0 replies; 27+ messages in thread
From: Jens Axboe @ 2009-05-25 7:34 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, hch, akpm, jack, yanmin_zhang, Jens Axboe
We see dirty inodes there occasionally, so better be safe and write them
out.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
fs/fs-writeback.c | 2 +-
include/linux/writeback.h | 1 +
mm/backing-dev.c | 16 +++++++++++-----
3 files changed, 13 insertions(+), 6 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 563860c..47f5ace 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -364,7 +364,7 @@ static void wb_writeback(struct bdi_writeback *wb)
* This will be inlined in bdi_writeback_task() once we get rid of any
* dirty inodes on the default_backing_dev_info
*/
-static void wb_do_writeback(struct bdi_writeback *wb)
+void wb_do_writeback(struct bdi_writeback *wb)
{
/*
* We get here in two cases:
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index baf04a9..e414702 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -69,6 +69,7 @@ void writeback_inodes(struct writeback_control *wbc);
int inode_wait(void *);
void sync_inodes_sb(struct super_block *, int wait);
void sync_inodes(int wait);
+void wb_do_writeback(struct bdi_writeback *wb);
/* writeback.h requires fs.h; it, too, is not included from here. */
static inline void wait_on_inode(struct inode *inode)
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 3e74041..3a032be 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -388,12 +388,14 @@ static int bdi_forker_task(void *ptr)
struct bdi_writeback *wb;
/*
- * Should never trigger on the default bdi
+ * Ideally we'd like not to see any dirty inodes on the
+ * default_backing_dev_info. Until these are tracked down,
+ * perform the same writeback here that bdi_writeback_task
+ * does. For logic, see comment in
+ * fs/fs-writeback.c:bdi_writeback_task()
*/
- if (wb_has_dirty_io(me)) {
- bdi_flush_io(me->bdi);
- WARN_ON(1);
- }
+ if (wb_has_dirty_io(me) || !list_empty(&me->bdi->work_list))
+ wb_do_writeback(me);
prepare_to_wait(&me->wait, &wait, TASK_INTERRUPTIBLE);
@@ -420,6 +422,10 @@ static int bdi_forker_task(void *ptr)
continue;
}
+ /*
+ * This is our real job - check for pending entries in
+ * bdi_pending_list, and create the tasks that got added
+ */
bdi = list_entry(bdi_pending_list.next, struct backing_dev_info,
bdi_list);
list_del_init(&bdi->bdi_list);
--
1.6.3.rc0.1.gf800
^ permalink raw reply related [flat|nested] 27+ messages in thread
* [PATCH 09/12] writeback: allow sleepy exit of default writeback task
2009-05-25 7:34 [PATCH 0/12] Per-bdi writeback flusher threads #5 Jens Axboe
` (7 preceding siblings ...)
2009-05-25 7:34 ` [PATCH 08/12] writeback: include default_backing_dev_info in writeback Jens Axboe
@ 2009-05-25 7:34 ` Jens Axboe
2009-05-25 7:34 ` [PATCH 10/12] writeback: add some debug inode list counters to bdi stats Jens Axboe
` (2 subsequent siblings)
11 siblings, 0 replies; 27+ messages in thread
From: Jens Axboe @ 2009-05-25 7:34 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, hch, akpm, jack, yanmin_zhang, Jens Axboe
Since we do lazy create of default writeback tasks for a bdi, we can
allow sleepy exit if it has been completely idle for 5 minutes.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
fs/fs-writeback.c | 52 ++++++++++++++++++++++++++++++++++--------
include/linux/backing-dev.h | 5 ++++
include/linux/writeback.h | 2 +-
3 files changed, 48 insertions(+), 11 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 47f5ace..1292a88 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -247,10 +247,10 @@ int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
* older_than_this takes precedence over nr_to_write. So we'll only write back
* all dirty pages if they are all attached to "old" mappings.
*/
-static void wb_kupdated(struct bdi_writeback *wb)
+static long wb_kupdated(struct bdi_writeback *wb)
{
unsigned long oldest_jif;
- long nr_to_write;
+ long nr_to_write, wrote = 0;
struct writeback_control wbc = {
.bdi = wb->bdi,
.sync_mode = WB_SYNC_NONE,
@@ -273,10 +273,13 @@ static void wb_kupdated(struct bdi_writeback *wb)
wbc.encountered_congestion = 0;
wbc.nr_to_write = MAX_WRITEBACK_PAGES;
generic_sync_wb_inodes(wb, NULL, &wbc);
+ wrote += MAX_WRITEBACK_PAGES - wbc.nr_to_write;
if (wbc.nr_to_write > 0)
break; /* All the old data is written */
nr_to_write -= MAX_WRITEBACK_PAGES;
}
+
+ return wrote;
}
static inline bool over_bground_thresh(void)
@@ -289,7 +292,7 @@ static inline bool over_bground_thresh(void)
global_page_state(NR_UNSTABLE_NFS) >= background_thresh);
}
-static void __wb_writeback(struct bdi_writeback *wb, long nr_pages,
+static long __wb_writeback(struct bdi_writeback *wb, long nr_pages,
struct super_block *sb,
enum writeback_sync_modes sync_mode)
{
@@ -299,6 +302,7 @@ static void __wb_writeback(struct bdi_writeback *wb, long nr_pages,
.older_than_this = NULL,
.range_cyclic = 1,
};
+ long wrote = 0;
for (;;) {
if (sync_mode == WB_SYNC_NONE && nr_pages <= 0 &&
@@ -311,6 +315,7 @@ static void __wb_writeback(struct bdi_writeback *wb, long nr_pages,
wbc.pages_skipped = 0;
generic_sync_wb_inodes(wb, sb, &wbc);
nr_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
+ wrote += MAX_WRITEBACK_PAGES - wbc.nr_to_write;
/*
* If we ran out of stuff to write, bail unless more_io got set
*/
@@ -320,6 +325,8 @@ static void __wb_writeback(struct bdi_writeback *wb, long nr_pages,
break;
}
}
+
+ return wrote;
}
/*
@@ -345,10 +352,11 @@ static struct bdi_work *get_next_work_item(struct backing_dev_info *bdi,
return ret;
}
-static void wb_writeback(struct bdi_writeback *wb)
+static long wb_writeback(struct bdi_writeback *wb)
{
struct backing_dev_info *bdi = wb->bdi;
struct bdi_work *work;
+ long wrote = 0;
while ((work = get_next_work_item(bdi, wb)) != NULL) {
struct super_block *sb = bdi_work_sb(work);
@@ -356,16 +364,20 @@ static void wb_writeback(struct bdi_writeback *wb)
enum writeback_sync_modes sync_mode = work->sync_mode;
wb_clear_pending(wb, work);
- __wb_writeback(wb, nr_pages, sb, sync_mode);
+ wrote += __wb_writeback(wb, nr_pages, sb, sync_mode);
}
+
+ return wrote;
}
/*
* This will be inlined in bdi_writeback_task() once we get rid of any
* dirty inodes on the default_backing_dev_info
*/
-void wb_do_writeback(struct bdi_writeback *wb)
+long wb_do_writeback(struct bdi_writeback *wb)
{
+ long wrote;
+
/*
* We get here in two cases:
*
@@ -377,9 +389,11 @@ void wb_do_writeback(struct bdi_writeback *wb)
* items on the work_list. Process those.
*/
if (list_empty(&wb->bdi->work_list))
- wb_kupdated(wb);
+ wrote = wb_kupdated(wb);
else
- wb_writeback(wb);
+ wrote = wb_writeback(wb);
+
+ return wrote;
}
/*
@@ -388,12 +402,30 @@ void wb_do_writeback(struct bdi_writeback *wb)
*/
int bdi_writeback_task(struct bdi_writeback *wb)
{
+ unsigned long last_active = jiffies;
+ unsigned long wait_jiffies = -1UL;
+ long pages_written;
DEFINE_WAIT(wait);
while (!kthread_should_stop()) {
- unsigned long wait_jiffies;
- wb_do_writeback(wb);
+ pages_written = wb_do_writeback(wb);
+
+ if (pages_written)
+ last_active = jiffies;
+ else if (wait_jiffies != -1UL) {
+ unsigned long max_idle;
+
+ /*
+ * Longest period of inactivity that we tolerate. If we
+ * see dirty data again later, the task will get
+ * recreated automatically.
+ */
+ max_idle = max(5UL * 60 * HZ, wait_jiffies);
+ if (time_after(jiffies, max_idle + last_active) &&
+ wb_is_default_task(wb))
+ break;
+ }
prepare_to_wait(&wb->wait, &wait, TASK_INTERRUPTIBLE);
wait_jiffies = msecs_to_jiffies(dirty_writeback_interval * 10);
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 72b4797..53e6c8d 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -113,6 +113,11 @@ int bdi_has_dirty_io(struct backing_dev_info *bdi);
extern struct mutex bdi_lock;
extern struct list_head bdi_list;
+static inline int wb_is_default_task(struct bdi_writeback *wb)
+{
+ return wb == &wb->bdi->wb;
+}
+
static inline int bdi_wblist_needs_lock(struct backing_dev_info *bdi)
{
return test_bit(BDI_wblist_lock, &bdi->state);
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index e414702..30e318b 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -69,7 +69,7 @@ void writeback_inodes(struct writeback_control *wbc);
int inode_wait(void *);
void sync_inodes_sb(struct super_block *, int wait);
void sync_inodes(int wait);
-void wb_do_writeback(struct bdi_writeback *wb);
+long wb_do_writeback(struct bdi_writeback *wb);
/* writeback.h requires fs.h; it, too, is not included from here. */
static inline void wait_on_inode(struct inode *inode)
--
1.6.3.rc0.1.gf800
^ permalink raw reply related [flat|nested] 27+ messages in thread
* [PATCH 10/12] writeback: add some debug inode list counters to bdi stats
2009-05-25 7:34 [PATCH 0/12] Per-bdi writeback flusher threads #5 Jens Axboe
` (8 preceding siblings ...)
2009-05-25 7:34 ` [PATCH 09/12] writeback: allow sleepy exit of default writeback task Jens Axboe
@ 2009-05-25 7:34 ` Jens Axboe
2009-05-25 7:34 ` [PATCH 11/12] writeback: add name to backing_dev_info Jens Axboe
2009-05-25 7:34 ` [PATCH 12/12] writeback: check for registered bdi in flusher add and inode dirty Jens Axboe
11 siblings, 0 replies; 27+ messages in thread
From: Jens Axboe @ 2009-05-25 7:34 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, hch, akpm, jack, yanmin_zhang, Jens Axboe
Add some debug entries to be able to inspect the internal state of
the writeback details.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
mm/backing-dev.c | 38 ++++++++++++++++++++++++++++++++++----
1 files changed, 34 insertions(+), 4 deletions(-)
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 3a032be..fcc0b2a 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -43,9 +43,29 @@ static void bdi_debug_init(void)
static int bdi_debug_stats_show(struct seq_file *m, void *v)
{
struct backing_dev_info *bdi = m->private;
+ struct bdi_writeback *wb;
unsigned long background_thresh;
unsigned long dirty_thresh;
unsigned long bdi_thresh;
+ unsigned long nr_dirty, nr_io, nr_more_io, nr_wb;
+ struct inode *inode;
+
+ /*
+ * inode lock is enough here, the bdi->wb_list is protected by
+ * RCU on the reader side
+ */
+ nr_wb = nr_dirty = nr_io = nr_more_io = 0;
+ spin_lock(&inode_lock);
+ list_for_each_entry(wb, &bdi->wb_list, list) {
+ nr_wb++;
+ list_for_each_entry(inode, &wb->b_dirty, i_list)
+ nr_dirty++;
+ list_for_each_entry(inode, &wb->b_io, i_list)
+ nr_io++;
+ list_for_each_entry(inode, &wb->b_more_io, i_list)
+ nr_more_io++;
+ }
+ spin_unlock(&inode_lock);
get_dirty_limits(&background_thresh, &dirty_thresh, &bdi_thresh, bdi);
@@ -55,12 +75,22 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v)
"BdiReclaimable: %8lu kB\n"
"BdiDirtyThresh: %8lu kB\n"
"DirtyThresh: %8lu kB\n"
- "BackgroundThresh: %8lu kB\n",
+ "BackgroundThresh: %8lu kB\n"
+ "WriteBack threads:%8lu\n"
+ "b_dirty: %8lu\n"
+ "b_io: %8lu\n"
+ "b_more_io: %8lu\n"
+ "bdi_list: %8u\n"
+ "state: %8lx\n"
+ "wb_mask: %8lx\n"
+ "wb_list: %8u\n"
+ "wb_cnt: %8u\n",
(unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)),
(unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)),
- K(bdi_thresh),
- K(dirty_thresh),
- K(background_thresh));
+ K(bdi_thresh), K(dirty_thresh),
+ K(background_thresh), nr_wb, nr_dirty, nr_io, nr_more_io,
+ !list_empty(&bdi->bdi_list), bdi->state, bdi->wb_mask,
+ !list_empty(&bdi->wb_list), bdi->wb_cnt);
#undef K
return 0;
--
1.6.3.rc0.1.gf800
^ permalink raw reply related [flat|nested] 27+ messages in thread
* [PATCH 11/12] writeback: add name to backing_dev_info
2009-05-25 7:34 [PATCH 0/12] Per-bdi writeback flusher threads #5 Jens Axboe
` (9 preceding siblings ...)
2009-05-25 7:34 ` [PATCH 10/12] writeback: add some debug inode list counters to bdi stats Jens Axboe
@ 2009-05-25 7:34 ` Jens Axboe
2009-05-25 7:34 ` [PATCH 12/12] writeback: check for registered bdi in flusher add and inode dirty Jens Axboe
11 siblings, 0 replies; 27+ messages in thread
From: Jens Axboe @ 2009-05-25 7:34 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, hch, akpm, jack, yanmin_zhang, Jens Axboe
This enables us to track who does what and print info. Its main use
is catching dirty inodes on the default_backing_dev_info, so we can
fix that up.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
block/blk-core.c | 1 +
drivers/block/aoe/aoeblk.c | 1 +
drivers/char/mem.c | 1 +
fs/btrfs/disk-io.c | 1 +
fs/char_dev.c | 1 +
fs/configfs/inode.c | 1 +
fs/fuse/inode.c | 1 +
fs/hugetlbfs/inode.c | 1 +
fs/nfs/client.c | 1 +
fs/ocfs2/dlm/dlmfs.c | 1 +
fs/ramfs/inode.c | 1 +
fs/sysfs/inode.c | 1 +
fs/ubifs/super.c | 1 +
include/linux/backing-dev.h | 2 ++
kernel/cgroup.c | 1 +
mm/backing-dev.c | 1 +
mm/swap_state.c | 1 +
17 files changed, 18 insertions(+), 0 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index c89883b..d3f18b5 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -517,6 +517,7 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
q->backing_dev_info.unplug_io_fn = blk_backing_dev_unplug;
q->backing_dev_info.unplug_io_data = q;
+ q->backing_dev_info.name = "block";
err = bdi_init(&q->backing_dev_info);
if (err) {
kmem_cache_free(blk_requestq_cachep, q);
diff --git a/drivers/block/aoe/aoeblk.c b/drivers/block/aoe/aoeblk.c
index 2307a27..0efb8fc 100644
--- a/drivers/block/aoe/aoeblk.c
+++ b/drivers/block/aoe/aoeblk.c
@@ -265,6 +265,7 @@ aoeblk_gdalloc(void *vp)
}
blk_queue_make_request(&d->blkq, aoeblk_make_request);
+ d->blkq.backing_dev_info.name = "aoe";
if (bdi_init(&d->blkq.backing_dev_info))
goto err_mempool;
spin_lock_irqsave(&d->lock, flags);
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 8f05c38..3b38093 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -820,6 +820,7 @@ static const struct file_operations zero_fops = {
* - permits private mappings, "copies" are taken of the source of zeros
*/
static struct backing_dev_info zero_bdi = {
+ .name = "char/mem",
.capabilities = BDI_CAP_MAP_COPY,
};
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 2dc19c9..eff2a82 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1353,6 +1353,7 @@ static int setup_bdi(struct btrfs_fs_info *info, struct backing_dev_info *bdi)
{
int err;
+ bdi->name = "btrfs";
bdi->capabilities = BDI_CAP_MAP_COPY;
err = bdi_init(bdi);
if (err)
diff --git a/fs/char_dev.c b/fs/char_dev.c
index 38f7122..350ef9c 100644
--- a/fs/char_dev.c
+++ b/fs/char_dev.c
@@ -32,6 +32,7 @@
* - no readahead or I/O queue unplugging required
*/
struct backing_dev_info directly_mappable_cdev_bdi = {
+ .name = "char",
.capabilities = (
#ifdef CONFIG_MMU
/* permit private copies of the data to be taken */
diff --git a/fs/configfs/inode.c b/fs/configfs/inode.c
index 5d349d3..9a266cd 100644
--- a/fs/configfs/inode.c
+++ b/fs/configfs/inode.c
@@ -46,6 +46,7 @@ static const struct address_space_operations configfs_aops = {
};
static struct backing_dev_info configfs_backing_dev_info = {
+ .name = "configfs",
.ra_pages = 0, /* No readahead */
.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
};
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 91f7c85..e5e8b03 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -484,6 +484,7 @@ int fuse_conn_init(struct fuse_conn *fc, struct super_block *sb)
INIT_LIST_HEAD(&fc->bg_queue);
INIT_LIST_HEAD(&fc->entry);
atomic_set(&fc->num_waiting, 0);
+ fc->bdi.name = "fuse";
fc->bdi.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
fc->bdi.unplug_io_fn = default_unplug_io_fn;
/* fuse does it's own writeback accounting */
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index c1462d4..db1e537 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -43,6 +43,7 @@ static const struct inode_operations hugetlbfs_dir_inode_operations;
static const struct inode_operations hugetlbfs_inode_operations;
static struct backing_dev_info hugetlbfs_backing_dev_info = {
+ .name = "hugetlbfs",
.ra_pages = 0, /* No readahead */
.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
};
diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 75c9cd2..3a26d06 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -836,6 +836,7 @@ static void nfs_server_set_fsinfo(struct nfs_server *server, struct nfs_fsinfo *
server->rsize = NFS_MAX_FILE_IO_SIZE;
server->rpages = (server->rsize + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+ server->backing_dev_info.name = "nfs";
server->backing_dev_info.ra_pages = server->rpages * NFS_MAX_READAHEAD;
if (server->wsize > max_rpc_payload)
diff --git a/fs/ocfs2/dlm/dlmfs.c b/fs/ocfs2/dlm/dlmfs.c
index 1c9efb4..02bf178 100644
--- a/fs/ocfs2/dlm/dlmfs.c
+++ b/fs/ocfs2/dlm/dlmfs.c
@@ -325,6 +325,7 @@ clear_fields:
}
static struct backing_dev_info dlmfs_backing_dev_info = {
+ .name = "ocfs2-dlmfs",
.ra_pages = 0, /* No readahead */
.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
};
diff --git a/fs/ramfs/inode.c b/fs/ramfs/inode.c
index 3a6b193..5a24199 100644
--- a/fs/ramfs/inode.c
+++ b/fs/ramfs/inode.c
@@ -46,6 +46,7 @@ static const struct super_operations ramfs_ops;
static const struct inode_operations ramfs_dir_inode_operations;
static struct backing_dev_info ramfs_backing_dev_info = {
+ .name = "ramfs",
.ra_pages = 0, /* No readahead */
.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK |
BDI_CAP_MAP_DIRECT | BDI_CAP_MAP_COPY |
diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index 555f0ff..e57f98e 100644
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -29,6 +29,7 @@ static const struct address_space_operations sysfs_aops = {
};
static struct backing_dev_info sysfs_backing_dev_info = {
+ .name = "sysfs",
.ra_pages = 0, /* No readahead */
.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
};
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index e9f7a75..2349e2c 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -1923,6 +1923,7 @@ static int ubifs_fill_super(struct super_block *sb, void *data, int silent)
*
* Read-ahead will be disabled because @c->bdi.ra_pages is 0.
*/
+ c->bdi.name = "ubifs",
c->bdi.capabilities = BDI_CAP_MAP_COPY;
c->bdi.unplug_io_fn = default_unplug_io_fn;
err = bdi_init(&c->bdi);
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 53e6c8d..4507569 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -70,6 +70,8 @@ struct backing_dev_info {
void (*unplug_io_fn)(struct backing_dev_info *, struct page *);
void *unplug_io_data;
+ char *name;
+
struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS];
struct prop_local_percpu completions;
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index a7267bf..0863c5f 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -598,6 +598,7 @@ static struct inode_operations cgroup_dir_inode_operations;
static struct file_operations proc_cgroupstats_operations;
static struct backing_dev_info cgroup_backing_dev_info = {
+ .name = "cgroup",
.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
};
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index fcc0b2a..0834ff9 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -17,6 +17,7 @@ void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
EXPORT_SYMBOL(default_unplug_io_fn);
struct backing_dev_info default_backing_dev_info = {
+ .name = "default",
.ra_pages = VM_MAX_READAHEAD * 1024 / PAGE_CACHE_SIZE,
.state = 0,
.capabilities = BDI_CAP_MAP_COPY | BDI_CAP_FLUSH_FORKER,
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 3ecea98..323da00 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -34,6 +34,7 @@ static const struct address_space_operations swap_aops = {
};
static struct backing_dev_info swap_backing_dev_info = {
+ .name = "swap",
.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
.unplug_io_fn = swap_unplug_io_fn,
};
--
1.6.3.rc0.1.gf800
^ permalink raw reply related [flat|nested] 27+ messages in thread
* [PATCH 12/12] writeback: check for registered bdi in flusher add and inode dirty
2009-05-25 7:34 [PATCH 0/12] Per-bdi writeback flusher threads #5 Jens Axboe
` (10 preceding siblings ...)
2009-05-25 7:34 ` [PATCH 11/12] writeback: add name to backing_dev_info Jens Axboe
@ 2009-05-25 7:34 ` Jens Axboe
11 siblings, 0 replies; 27+ messages in thread
From: Jens Axboe @ 2009-05-25 7:34 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, hch, akpm, jack, yanmin_zhang, Jens Axboe
Also a debugging aid. We want to catch dirty inodes being added to
backing devices that don't do writeback.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
fs/fs-writeback.c | 7 +++++++
include/linux/backing-dev.h | 1 +
mm/backing-dev.c | 6 ++++++
3 files changed, 14 insertions(+), 0 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 1292a88..bf8e0d5 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -583,6 +583,13 @@ void __mark_inode_dirty(struct inode *inode, int flags)
*/
if (!was_dirty) {
struct bdi_writeback *wb = inode_get_wb(inode);
+ struct backing_dev_info *bdi = wb->bdi;
+
+ if (bdi_cap_writeback_dirty(bdi) &&
+ !test_bit(BDI_registered, &bdi->state)) {
+ WARN_ON(1);
+ printk("bdi-%s not registered\n", bdi->name);
+ }
inode->dirtied_when = jiffies;
list_move(&inode->i_list, &wb->b_dirty);
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 4507569..0b20d4b 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -31,6 +31,7 @@ enum bdi_state {
BDI_wblist_lock, /* bdi->wb_list now needs locking */
BDI_async_congested, /* The async (write) queue is getting full */
BDI_sync_congested, /* The sync queue is getting full */
+ BDI_registered, /* bdi_register() was done */
BDI_unused, /* Available bits start here */
};
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 0834ff9..ed66081 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -504,6 +504,11 @@ static void bdi_add_one_flusher_task(struct backing_dev_info *bdi,
if (!bdi_cap_writeback_dirty(bdi))
return;
+ if (WARN_ON(!test_bit(BDI_registered, &bdi->state))) {
+ printk("bdi %p/%s is not registered!\n", bdi, bdi->name);
+ return;
+ }
+
/*
* Check with the helper whether to proceed adding a task. Will only
* abort if we two or more simultanous calls to
@@ -612,6 +617,7 @@ remove_err:
}
bdi_debug_register(bdi, dev_name(dev));
+ set_bit(BDI_registered, &bdi->state);
exit:
return ret;
}
--
1.6.3.rc0.1.gf800
^ permalink raw reply related [flat|nested] 27+ messages in thread
* Re: [PATCH 03/12] writeback: move dirty inodes from super_block to backing_dev_info
2009-05-25 7:34 ` [PATCH 03/12] writeback: move dirty inodes from super_block to backing_dev_info Jens Axboe
@ 2009-05-25 8:42 ` Jan Kara
2009-05-25 8:51 ` Jens Axboe
0 siblings, 1 reply; 27+ messages in thread
From: Jan Kara @ 2009-05-25 8:42 UTC (permalink / raw)
To: Jens Axboe
Cc: linux-kernel, linux-fsdevel, chris.mason, david, hch, akpm, jack,
yanmin_zhang
On Mon 25-05-09 09:34:38, Jens Axboe wrote:
> This is a first step at introducing per-bdi flusher threads. We should
> have no change in behaviour, although sb_has_dirty_inodes() is now
> ridiculously expensive, as there's no easy way to answer that question.
> Not a huge problem, since it'll be deleted in subsequent patches.
>
> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
> ---
> fs/fs-writeback.c | 196 +++++++++++++++++++++++++++---------------
> fs/super.c | 3 -
> include/linux/backing-dev.h | 9 ++
> include/linux/fs.h | 5 +-
> mm/backing-dev.c | 30 +++++++
> mm/page-writeback.c | 11 +--
> 6 files changed, 170 insertions(+), 84 deletions(-)
...
> @@ -225,9 +231,23 @@ int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)
> }
> EXPORT_SYMBOL(bdi_register_dev);
>
> +static void bdi_remove_from_list(struct backing_dev_info *bdi)
> +{
> + mutex_lock(&bdi_lock);
> + list_del_rcu(&bdi->bdi_list);
> + mutex_unlock(&bdi_lock);
> +
> + /*
> + * In case the bdi is freed right after unregister, we need to
> + * make sure any RCU sections have exited
> + */
> + synchronize_rcu();
> +}
> +
Is this RCU thing still valid? And in bdi_register_dev() as well...
Honza
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
^ permalink raw reply [flat|nested] 27+ messages in thread
* Re: [PATCH 03/12] writeback: move dirty inodes from super_block to backing_dev_info
2009-05-25 8:42 ` Jan Kara
@ 2009-05-25 8:51 ` Jens Axboe
0 siblings, 0 replies; 27+ messages in thread
From: Jens Axboe @ 2009-05-25 8:51 UTC (permalink / raw)
To: Jan Kara
Cc: linux-kernel, linux-fsdevel, chris.mason, david, hch, akpm, yanmin_zhang
On Mon, May 25 2009, Jan Kara wrote:
> On Mon 25-05-09 09:34:38, Jens Axboe wrote:
> > This is a first step at introducing per-bdi flusher threads. We should
> > have no change in behaviour, although sb_has_dirty_inodes() is now
> > ridiculously expensive, as there's no easy way to answer that question.
> > Not a huge problem, since it'll be deleted in subsequent patches.
> >
> > Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
> > ---
> > fs/fs-writeback.c | 196 +++++++++++++++++++++++++++---------------
> > fs/super.c | 3 -
> > include/linux/backing-dev.h | 9 ++
> > include/linux/fs.h | 5 +-
> > mm/backing-dev.c | 30 +++++++
> > mm/page-writeback.c | 11 +--
> > 6 files changed, 170 insertions(+), 84 deletions(-)
> ...
> > @@ -225,9 +231,23 @@ int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)
> > }
> > EXPORT_SYMBOL(bdi_register_dev);
> >
> > +static void bdi_remove_from_list(struct backing_dev_info *bdi)
> > +{
> > + mutex_lock(&bdi_lock);
> > + list_del_rcu(&bdi->bdi_list);
> > + mutex_unlock(&bdi_lock);
> > +
> > + /*
> > + * In case the bdi is freed right after unregister, we need to
> > + * make sure any RCU sections have exited
> > + */
> > + synchronize_rcu();
> > +}
> > +
> Is this RCU thing still valid? And in bdi_register_dev() as well...
Not it isn't, apparently that bit didn't get killed from the intermedia
steps. The final version doesn't contain any RCU for
bdi_list/bdi_pending_list. I'll shuffle this back as well, thanks for
noticing!
--
Jens Axboe
^ permalink raw reply [flat|nested] 27+ messages in thread
* Re: [PATCH 04/12] writeback: switch to per-bdi threads for flushing data
2009-05-25 7:34 ` [PATCH 04/12] writeback: switch to per-bdi threads for flushing data Jens Axboe
@ 2009-05-25 9:58 ` Jan Kara
2009-05-25 10:34 ` Jens Axboe
2009-05-26 8:56 ` Jens Axboe
0 siblings, 2 replies; 27+ messages in thread
From: Jan Kara @ 2009-05-25 9:58 UTC (permalink / raw)
To: Jens Axboe
Cc: linux-kernel, linux-fsdevel, chris.mason, david, hch, akpm, jack,
yanmin_zhang
Hi Jens,
I've noticed a few more things:
On Mon 25-05-09 09:34:39, Jens Axboe wrote:
> diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
> index 1137408..7cb4d02 100644
> --- a/fs/fs-writeback.c
> +++ b/fs/fs-writeback.c
> @@ -19,6 +19,8 @@
> #include <linux/sched.h>
> #include <linux/fs.h>
> #include <linux/mm.h>
> +#include <linux/kthread.h>
> +#include <linux/freezer.h>
> #include <linux/writeback.h>
> #include <linux/blkdev.h>
> #include <linux/backing-dev.h>
> @@ -61,10 +63,193 @@ int writeback_in_progress(struct backing_dev_info *bdi)
> */
> static void writeback_release(struct backing_dev_info *bdi)
> {
> - BUG_ON(!writeback_in_progress(bdi));
> + WARN_ON_ONCE(!writeback_in_progress(bdi));
> + bdi->wb_arg.nr_pages = 0;
> + bdi->wb_arg.sb = NULL;
> clear_bit(BDI_pdflush, &bdi->state);
> }
>
> +int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
> + long nr_pages, enum writeback_sync_modes sync_mode)
> +{
> + /*
> + * This only happens the first time someone kicks this bdi, so put
> + * it out-of-line.
> + */
> + if (unlikely(!bdi->task)) {
> + bdi_add_default_flusher_task(bdi);
> + return 1;
> + }
> +
> + if (writeback_acquire(bdi)) {
> + bdi->wb_arg.nr_pages = nr_pages;
> + bdi->wb_arg.sb = sb;
> + bdi->wb_arg.sync_mode = sync_mode;
> + /*
> + * make above store seen before the task is woken
> + */
> + smp_mb();
> + wake_up(&bdi->wait);
> + }
Hmm, wouldn't the interface be more useful if we could just pass down the
whole writeback_control to the flusher threads?
Maybe a real question is, what should be the role of flusher threads?
Should they be just threads for kupdate / pdflush style writeout or do we
expect them to be used also for other cases when we need to submit IO to
the BDI?
> +
> + return 0;
> +}
> +
> +/*
> + * The maximum number of pages to writeout in a single bdi flush/kupdate
> + * operation. We do this so we don't hold I_SYNC against an inode for
> + * enormous amounts of time, which would block a userspace task which has
> + * been forced to throttle against that inode. Also, the code reevaluates
> + * the dirty each time it has written this many pages.
> + */
> +#define MAX_WRITEBACK_PAGES 1024
> +
> +/*
> + * Periodic writeback of "old" data.
> + *
> + * Define "old": the first time one of an inode's pages is dirtied, we mark the
> + * dirtying-time in the inode's address_space. So this periodic writeback code
> + * just walks the superblock inode list, writing back any inodes which are
> + * older than a specific point in time.
> + *
> + * Try to run once per dirty_writeback_interval. But if a writeback event
> + * takes longer than a dirty_writeback_interval interval, then leave a
> + * one-second gap.
> + *
> + * older_than_this takes precedence over nr_to_write. So we'll only write back
> + * all dirty pages if they are all attached to "old" mappings.
> + */
> +static void bdi_kupdated(struct backing_dev_info *bdi)
> +{
> + unsigned long oldest_jif;
> + long nr_to_write;
> + struct writeback_control wbc = {
> + .bdi = bdi,
> + .sync_mode = WB_SYNC_NONE,
> + .older_than_this = &oldest_jif,
> + .nr_to_write = 0,
> + .for_kupdate = 1,
> + .range_cyclic = 1,
> + };
> +
> + sync_supers();
Hmm, so each BDI flusher thread is going to sync all the superblocks?
Isn't there a better way? I suppose we *should* be able to somehow go
from a BDI to a superblock (or maybe a list of those) so that we can write
per-fs metadata not bound to inodes.
> +
> + oldest_jif = jiffies - msecs_to_jiffies(dirty_expire_interval * 10);
> +
> + nr_to_write = global_page_state(NR_FILE_DIRTY) +
> + global_page_state(NR_UNSTABLE_NFS) +
> + (inodes_stat.nr_inodes - inodes_stat.nr_unused);
> +
> + while (nr_to_write > 0) {
> + wbc.more_io = 0;
> + wbc.encountered_congestion = 0;
> + wbc.nr_to_write = MAX_WRITEBACK_PAGES;
> + generic_sync_bdi_inodes(NULL, &wbc);
> + if (wbc.nr_to_write > 0)
> + break; /* All the old data is written */
> + nr_to_write -= MAX_WRITEBACK_PAGES;
> + }
> +}
> +
> +static inline bool over_bground_thresh(void)
> +{
> + unsigned long background_thresh, dirty_thresh;
> +
> + get_dirty_limits(&background_thresh, &dirty_thresh, NULL, NULL);
> +
> + return (global_page_state(NR_FILE_DIRTY) +
> + global_page_state(NR_UNSTABLE_NFS) >= background_thresh);
> +}
> +
> +static void bdi_pdflush(struct backing_dev_info *bdi)
> +{
> + struct writeback_control wbc = {
> + .bdi = bdi,
> + .sync_mode = bdi->wb_arg.sync_mode,
> + .older_than_this = NULL,
> + .range_cyclic = 1,
> + };
> + long nr_pages = bdi->wb_arg.nr_pages;
> +
> + for (;;) {
> + if (wbc.sync_mode == WB_SYNC_NONE && nr_pages <= 0 &&
> + !over_bground_thresh())
> + break;
> +
> + wbc.more_io = 0;
> + wbc.encountered_congestion = 0;
> + wbc.nr_to_write = MAX_WRITEBACK_PAGES;
> + wbc.pages_skipped = 0;
> + generic_sync_bdi_inodes(bdi->wb_arg.sb, &wbc);
> + nr_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
> + /*
> + * If we ran out of stuff to write, bail unless more_io got set
> + */
> + if (wbc.nr_to_write > 0 || wbc.pages_skipped > 0) {
> + if (wbc.more_io)
> + continue;
> + break;
> + }
> + }
> +}
> +
> +/*
> + * Handle writeback of dirty data for the device backed by this bdi. Also
> + * wakes up periodically and does kupdated style flushing.
> + */
> +int bdi_writeback_task(struct backing_dev_info *bdi)
> +{
> + while (!kthread_should_stop()) {
> + unsigned long wait_jiffies;
> + DEFINE_WAIT(wait);
> +
> + prepare_to_wait(&bdi->wait, &wait, TASK_INTERRUPTIBLE);
> + wait_jiffies = msecs_to_jiffies(dirty_writeback_interval * 10);
> + schedule_timeout(wait_jiffies);
> + try_to_freeze();
> +
> + /*
> + * We get here in two cases:
> + *
> + * schedule_timeout() returned because the dirty writeback
> + * interval has elapsed. If that happens, we will be able
> + * to acquire the writeback lock and will proceed to do
> + * kupdated style writeout.
> + *
> + * Someone called bdi_start_writeback(), which will acquire
> + * the writeback lock. This means our writeback_acquire()
> + * below will fail and we call into bdi_pdflush() for
> + * pdflush style writeout.
> + *
> + */
> + if (writeback_acquire(bdi))
> + bdi_kupdated(bdi);
> + else
> + bdi_pdflush(bdi);
> +
> + writeback_release(bdi);
> + finish_wait(&bdi->wait, &wait);
> + }
Hmm, what does protect this thread from racing with umount? Note that old
flusher threads took s_umount semaphore and also elevated sb->s_count.
If everything is fine, we should have a comment somewhere around here what
stops umount from removing things under us or why it does not matter...
Maybe this is the reason of the oopses Yanmin saw.
BTW, one more difference here: Previously, if pdflush saw congestion on
the device, it did congestion_wait() and retried. Now it end's up waiting
whole dirty_writeback_interval so it should result in a bursty writeback on
a slow disk, couldn't it?
> +
> + return 0;
> +}
> +
> +void bdi_writeback_all(struct super_block *sb, long nr_pages,
> + enum writeback_sync_modes sync_mode)
> +{
> + struct backing_dev_info *bdi, *tmp;
> +
> + mutex_lock(&bdi_lock);
> +
> + list_for_each_entry_safe(bdi, tmp, &bdi_list, bdi_list) {
> + if (!bdi_has_dirty_io(bdi))
> + continue;
> + bdi_start_writeback(bdi, sb, nr_pages, sync_mode);
> + }
> +
> + mutex_unlock(&bdi_lock);
> +}
> +
> /**
> * __mark_inode_dirty - internal function
> * @inode: inode to mark
...
> @@ -591,13 +718,10 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
> void generic_sync_sb_inodes(struct super_block *sb,
> struct writeback_control *wbc)
> {
> - const int is_blkdev_sb = sb_is_blkdev_sb(sb);
> - struct backing_dev_info *bdi;
> -
> - mutex_lock(&bdi_lock);
> - list_for_each_entry(bdi, &bdi_list, bdi_list)
> - generic_sync_bdi_inodes(bdi, wbc, sb, is_blkdev_sb);
> - mutex_unlock(&bdi_lock);
> + if (wbc->bdi)
> + generic_sync_bdi_inodes(sb, wbc);
> + else
> + bdi_writeback_all(sb, wbc->nr_to_write, wbc->sync_mode);
Hmm, you write in the changelog that bdi_writeback_all() writes inline
now but AFAICS it still happens through the writeback threads. Which, on a
second though probably *is* what we want because we want writeback to go in
parallel on all devices we have.
...
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index 7c44314..54a4a65 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -36,15 +36,6 @@
> #include <linux/pagevec.h>
>
> /*
> - * The maximum number of pages to writeout in a single bdflush/kupdate
> - * operation. We do this so we don't hold I_SYNC against an inode for
> - * enormous amounts of time, which would block a userspace task which has
> - * been forced to throttle against that inode. Also, the code reevaluates
> - * the dirty each time it has written this many pages.
> - */
> -#define MAX_WRITEBACK_PAGES 1024
> -
> -/*
> * After a CPU has dirtied this many pages, balance_dirty_pages_ratelimited
> * will look to see if it needs to force writeback or throttling.
> */
> @@ -117,8 +108,6 @@ EXPORT_SYMBOL(laptop_mode);
> /* End of sysctl-exported parameters */
>
>
> -static void background_writeout(unsigned long _min_pages);
> -
> /*
> * Scale the writeback cache size proportional to the relative writeout speeds.
> *
> @@ -539,7 +528,7 @@ static void balance_dirty_pages(struct address_space *mapping)
> * been flushed to permanent storage.
> */
> if (bdi_nr_reclaimable) {
> - writeback_inodes(&wbc);
> + generic_sync_bdi_inodes(NULL, &wbc);
> pages_written += write_chunk - wbc.nr_to_write;
> get_dirty_limits(&background_thresh, &dirty_thresh,
> &bdi_thresh, bdi);
> @@ -590,7 +579,7 @@ static void balance_dirty_pages(struct address_space *mapping)
> (!laptop_mode && (global_page_state(NR_FILE_DIRTY)
> + global_page_state(NR_UNSTABLE_NFS)
> > background_thresh)))
> - pdflush_operation(background_writeout, 0);
> + bdi_start_writeback(bdi, NULL, 0, WB_SYNC_NONE);
> }
>
> void set_page_dirty_balance(struct page *page, int page_mkwrite)
> @@ -675,152 +664,36 @@ void throttle_vm_writeout(gfp_t gfp_mask)
> }
>
> /*
> - * writeback at least _min_pages, and keep writing until the amount of dirty
> - * memory is less than the background threshold, or until we're all clean.
> - */
> -static void background_writeout(unsigned long _min_pages)
> -{
> - long min_pages = _min_pages;
> - struct writeback_control wbc = {
> - .bdi = NULL,
> - .sync_mode = WB_SYNC_NONE,
> - .older_than_this = NULL,
> - .nr_to_write = 0,
> - .nonblocking = 1,
> - .range_cyclic = 1,
> - };
> -
> - for ( ; ; ) {
> - unsigned long background_thresh;
> - unsigned long dirty_thresh;
> -
> - get_dirty_limits(&background_thresh, &dirty_thresh, NULL, NULL);
> - if (global_page_state(NR_FILE_DIRTY) +
> - global_page_state(NR_UNSTABLE_NFS) < background_thresh
> - && min_pages <= 0)
> - break;
> - wbc.more_io = 0;
> - wbc.encountered_congestion = 0;
> - wbc.nr_to_write = MAX_WRITEBACK_PAGES;
> - wbc.pages_skipped = 0;
> - writeback_inodes(&wbc);
> - min_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
> - if (wbc.nr_to_write > 0 || wbc.pages_skipped > 0) {
> - /* Wrote less than expected */
> - if (wbc.encountered_congestion || wbc.more_io)
> - congestion_wait(WRITE, HZ/10);
> - else
> - break;
> - }
> - }
> -}
> -
> -/*
> * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back
> * the whole world. Returns 0 if a pdflush thread was dispatched. Returns
> * -1 if all pdflush threads were busy.
> */
> -int wakeup_pdflush(long nr_pages)
> +void wakeup_flusher_threads(long nr_pages)
> {
> if (nr_pages == 0)
> nr_pages = global_page_state(NR_FILE_DIRTY) +
> global_page_state(NR_UNSTABLE_NFS);
> - return pdflush_operation(background_writeout, nr_pages);
> + bdi_writeback_all(NULL, nr_pages, WB_SYNC_NONE);
> + return;
> }
...
> -
> -static void laptop_flush(unsigned long unused)
> -{
> - sys_sync();
> -}
> -
> static void laptop_timer_fn(unsigned long unused)
> {
> - pdflush_operation(laptop_flush, 0);
> + wakeup_flusher_threads(0);
> }
>
> /*
Here you significantly change the behavior of laptop mode - previously it
reliably synced all the data to disk once the "laptop writeout timeout"
elapsed. The idea is that we want to write all the dirty data we have so
that the drive can go to sleep for a longer period.
Now you changed that to asynchronous WB_SYNC_NONE writeback of some
number of pages. In particular if the disk gets congested, we'll just stop
doing writeback which probably isn't what we want for laptop mode...
Honza
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
^ permalink raw reply [flat|nested] 27+ messages in thread
* Re: [PATCH 06/12] writeback: separate the flushing state/task from the bdi
2009-05-25 7:34 ` [PATCH 06/12] writeback: separate the flushing state/task from the bdi Jens Axboe
@ 2009-05-25 10:13 ` Jan Kara
2009-05-25 10:36 ` Jens Axboe
0 siblings, 1 reply; 27+ messages in thread
From: Jan Kara @ 2009-05-25 10:13 UTC (permalink / raw)
To: Jens Axboe
Cc: linux-kernel, linux-fsdevel, chris.mason, david, hch, akpm, jack,
yanmin_zhang
On Mon 25-05-09 09:34:41, Jens Axboe wrote:
> Add a struct bdi_writeback for tracking and handling dirty IO. This
> is in preparation for adding > 1 flusher task per bdi.
>
> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
...
> static int bdi_start_fn(void *ptr)
> {
> - struct backing_dev_info *bdi = ptr;
> + struct bdi_writeback *wb = ptr;
> + struct backing_dev_info *bdi = wb->bdi;
> struct task_struct *tsk = current;
> -
> - /*
> - * Add us to the active bdi_list
> - */
> - mutex_lock(&bdi_lock);
> - list_add(&bdi->bdi_list, &bdi_list);
> - mutex_unlock(&bdi_lock);
I'm probably missing something but I cannot find where the bdi is added
to the bdi_list after this patch...
Honza
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
^ permalink raw reply [flat|nested] 27+ messages in thread
* Re: [PATCH 04/12] writeback: switch to per-bdi threads for flushing data
2009-05-25 9:58 ` Jan Kara
@ 2009-05-25 10:34 ` Jens Axboe
2009-05-25 12:10 ` Jan Kara
2009-05-26 8:56 ` Jens Axboe
1 sibling, 1 reply; 27+ messages in thread
From: Jens Axboe @ 2009-05-25 10:34 UTC (permalink / raw)
To: Jan Kara
Cc: linux-kernel, linux-fsdevel, chris.mason, david, hch, akpm, yanmin_zhang
On Mon, May 25 2009, Jan Kara wrote:
> Hi Jens,
>
> I've noticed a few more things:
>
> On Mon 25-05-09 09:34:39, Jens Axboe wrote:
> > diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
> > index 1137408..7cb4d02 100644
> > --- a/fs/fs-writeback.c
> > +++ b/fs/fs-writeback.c
> > @@ -19,6 +19,8 @@
> > #include <linux/sched.h>
> > #include <linux/fs.h>
> > #include <linux/mm.h>
> > +#include <linux/kthread.h>
> > +#include <linux/freezer.h>
> > #include <linux/writeback.h>
> > #include <linux/blkdev.h>
> > #include <linux/backing-dev.h>
> > @@ -61,10 +63,193 @@ int writeback_in_progress(struct backing_dev_info *bdi)
> > */
> > static void writeback_release(struct backing_dev_info *bdi)
> > {
> > - BUG_ON(!writeback_in_progress(bdi));
> > + WARN_ON_ONCE(!writeback_in_progress(bdi));
> > + bdi->wb_arg.nr_pages = 0;
> > + bdi->wb_arg.sb = NULL;
> > clear_bit(BDI_pdflush, &bdi->state);
> > }
> >
> > +int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
> > + long nr_pages, enum writeback_sync_modes sync_mode)
> > +{
> > + /*
> > + * This only happens the first time someone kicks this bdi, so put
> > + * it out-of-line.
> > + */
> > + if (unlikely(!bdi->task)) {
> > + bdi_add_default_flusher_task(bdi);
> > + return 1;
> > + }
> > +
> > + if (writeback_acquire(bdi)) {
> > + bdi->wb_arg.nr_pages = nr_pages;
> > + bdi->wb_arg.sb = sb;
> > + bdi->wb_arg.sync_mode = sync_mode;
> > + /*
> > + * make above store seen before the task is woken
> > + */
> > + smp_mb();
> > + wake_up(&bdi->wait);
> > + }
> Hmm, wouldn't the interface be more useful if we could just pass down the
> whole writeback_control to the flusher threads?
Yeah, that's what the later patch does too, when support for > 1 thread
has been added.
> Maybe a real question is, what should be the role of flusher threads?
> Should they be just threads for kupdate / pdflush style writeout or do we
> expect them to be used also for other cases when we need to submit IO to
> the BDI?
The thought has occured to me to punt other types of work to these
threads, now that we have them available. I haven't really thought that
through yet (and other changes may be required too), but it could be
things like async IO or even simple things like the unplugging that is
now done by kblockd.
> > + * The maximum number of pages to writeout in a single bdi flush/kupdate
> > + * operation. We do this so we don't hold I_SYNC against an inode for
> > + * enormous amounts of time, which would block a userspace task which has
> > + * been forced to throttle against that inode. Also, the code reevaluates
> > + * the dirty each time it has written this many pages.
> > + */
> > +#define MAX_WRITEBACK_PAGES 1024
> > +
> > +/*
> > + * Periodic writeback of "old" data.
> > + *
> > + * Define "old": the first time one of an inode's pages is dirtied, we mark the
> > + * dirtying-time in the inode's address_space. So this periodic writeback code
> > + * just walks the superblock inode list, writing back any inodes which are
> > + * older than a specific point in time.
> > + *
> > + * Try to run once per dirty_writeback_interval. But if a writeback event
> > + * takes longer than a dirty_writeback_interval interval, then leave a
> > + * one-second gap.
> > + *
> > + * older_than_this takes precedence over nr_to_write. So we'll only write back
> > + * all dirty pages if they are all attached to "old" mappings.
> > + */
> > +static void bdi_kupdated(struct backing_dev_info *bdi)
> > +{
> > + unsigned long oldest_jif;
> > + long nr_to_write;
> > + struct writeback_control wbc = {
> > + .bdi = bdi,
> > + .sync_mode = WB_SYNC_NONE,
> > + .older_than_this = &oldest_jif,
> > + .nr_to_write = 0,
> > + .for_kupdate = 1,
> > + .range_cyclic = 1,
> > + };
> > +
> > + sync_supers();
> Hmm, so each BDI flusher thread is going to sync all the superblocks?
> Isn't there a better way? I suppose we *should* be able to somehow go
> from a BDI to a superblock (or maybe a list of those) so that we can write
> per-fs metadata not bound to inodes.
Good catch, we should probably have that be sync_supers_bdi() and have a
way to leaf through the super(s) that are mounted on this bdi. Added to
the list.
> > +
> > + oldest_jif = jiffies - msecs_to_jiffies(dirty_expire_interval * 10);
> > +
> > + nr_to_write = global_page_state(NR_FILE_DIRTY) +
> > + global_page_state(NR_UNSTABLE_NFS) +
> > + (inodes_stat.nr_inodes - inodes_stat.nr_unused);
> > +
> > + while (nr_to_write > 0) {
> > + wbc.more_io = 0;
> > + wbc.encountered_congestion = 0;
> > + wbc.nr_to_write = MAX_WRITEBACK_PAGES;
> > + generic_sync_bdi_inodes(NULL, &wbc);
> > + if (wbc.nr_to_write > 0)
> > + break; /* All the old data is written */
> > + nr_to_write -= MAX_WRITEBACK_PAGES;
> > + }
> > +}
> > +
> > +static inline bool over_bground_thresh(void)
> > +{
> > + unsigned long background_thresh, dirty_thresh;
> > +
> > + get_dirty_limits(&background_thresh, &dirty_thresh, NULL, NULL);
> > +
> > + return (global_page_state(NR_FILE_DIRTY) +
> > + global_page_state(NR_UNSTABLE_NFS) >= background_thresh);
> > +}
> > +
> > +static void bdi_pdflush(struct backing_dev_info *bdi)
> > +{
> > + struct writeback_control wbc = {
> > + .bdi = bdi,
> > + .sync_mode = bdi->wb_arg.sync_mode,
> > + .older_than_this = NULL,
> > + .range_cyclic = 1,
> > + };
> > + long nr_pages = bdi->wb_arg.nr_pages;
> > +
> > + for (;;) {
> > + if (wbc.sync_mode == WB_SYNC_NONE && nr_pages <= 0 &&
> > + !over_bground_thresh())
> > + break;
> > +
> > + wbc.more_io = 0;
> > + wbc.encountered_congestion = 0;
> > + wbc.nr_to_write = MAX_WRITEBACK_PAGES;
> > + wbc.pages_skipped = 0;
> > + generic_sync_bdi_inodes(bdi->wb_arg.sb, &wbc);
> > + nr_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
> > + /*
> > + * If we ran out of stuff to write, bail unless more_io got set
> > + */
> > + if (wbc.nr_to_write > 0 || wbc.pages_skipped > 0) {
> > + if (wbc.more_io)
> > + continue;
> > + break;
> > + }
> > + }
> > +}
> > +
> > +/*
> > + * Handle writeback of dirty data for the device backed by this bdi. Also
> > + * wakes up periodically and does kupdated style flushing.
> > + */
> > +int bdi_writeback_task(struct backing_dev_info *bdi)
> > +{
> > + while (!kthread_should_stop()) {
> > + unsigned long wait_jiffies;
> > + DEFINE_WAIT(wait);
> > +
> > + prepare_to_wait(&bdi->wait, &wait, TASK_INTERRUPTIBLE);
> > + wait_jiffies = msecs_to_jiffies(dirty_writeback_interval * 10);
> > + schedule_timeout(wait_jiffies);
> > + try_to_freeze();
> > +
> > + /*
> > + * We get here in two cases:
> > + *
> > + * schedule_timeout() returned because the dirty writeback
> > + * interval has elapsed. If that happens, we will be able
> > + * to acquire the writeback lock and will proceed to do
> > + * kupdated style writeout.
> > + *
> > + * Someone called bdi_start_writeback(), which will acquire
> > + * the writeback lock. This means our writeback_acquire()
> > + * below will fail and we call into bdi_pdflush() for
> > + * pdflush style writeout.
> > + *
> > + */
> > + if (writeback_acquire(bdi))
> > + bdi_kupdated(bdi);
> > + else
> > + bdi_pdflush(bdi);
> > +
> > + writeback_release(bdi);
> > + finish_wait(&bdi->wait, &wait);
> > + }
> Hmm, what does protect this thread from racing with umount? Note that old
> flusher threads took s_umount semaphore and also elevated sb->s_count.
> If everything is fine, we should have a comment somewhere around here what
> stops umount from removing things under us or why it does not matter...
> Maybe this is the reason of the oopses Yanmin saw.
I think it was that oops, it got fixed by generic_sync_sb_inodes() doing
sync writeout again. So I think what happened is that it closed that
hole, but there could still be trouble. I'll look into that as well.
> BTW, one more difference here: Previously, if pdflush saw congestion on
> the device, it did congestion_wait() and retried. Now it end's up waiting
> whole dirty_writeback_interval so it should result in a bursty writeback on
> a slow disk, couldn't it?
Now it'll block on the queue instead of giving up, so in my opinion that
should provide smoother writeout. From the tests I did, it does.
> > +void bdi_writeback_all(struct super_block *sb, long nr_pages,
> > + enum writeback_sync_modes sync_mode)
> > +{
> > + struct backing_dev_info *bdi, *tmp;
> > +
> > + mutex_lock(&bdi_lock);
> > +
> > + list_for_each_entry_safe(bdi, tmp, &bdi_list, bdi_list) {
> > + if (!bdi_has_dirty_io(bdi))
> > + continue;
> > + bdi_start_writeback(bdi, sb, nr_pages, sync_mode);
> > + }
> > +
> > + mutex_unlock(&bdi_lock);
> > +}
> > +
> > /**
> > * __mark_inode_dirty - internal function
> > * @inode: inode to mark
> ...
> > @@ -591,13 +718,10 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
> > void generic_sync_sb_inodes(struct super_block *sb,
> > struct writeback_control *wbc)
> > {
> > - const int is_blkdev_sb = sb_is_blkdev_sb(sb);
> > - struct backing_dev_info *bdi;
> > -
> > - mutex_lock(&bdi_lock);
> > - list_for_each_entry(bdi, &bdi_list, bdi_list)
> > - generic_sync_bdi_inodes(bdi, wbc, sb, is_blkdev_sb);
> > - mutex_unlock(&bdi_lock);
> > + if (wbc->bdi)
> > + generic_sync_bdi_inodes(sb, wbc);
> > + else
> > + bdi_writeback_all(sb, wbc->nr_to_write, wbc->sync_mode);
> Hmm, you write in the changelog that bdi_writeback_all() writes inline
> now but AFAICS it still happens through the writeback threads. Which, on a
> second though probably *is* what we want because we want writeback to go in
> parallel on all devices we have.
Note that this is patch 4, later it is sync. But yes, I think it should
be async as well, but we do need a way to wait on the submitted work to
be processed in case of WB_SYNC_ALL.
> > * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back
> > * the whole world. Returns 0 if a pdflush thread was dispatched. Returns
> > * -1 if all pdflush threads were busy.
> > */
> > -int wakeup_pdflush(long nr_pages)
> > +void wakeup_flusher_threads(long nr_pages)
> > {
> > if (nr_pages == 0)
> > nr_pages = global_page_state(NR_FILE_DIRTY) +
> > global_page_state(NR_UNSTABLE_NFS);
> > - return pdflush_operation(background_writeout, nr_pages);
> > + bdi_writeback_all(NULL, nr_pages, WB_SYNC_NONE);
> > + return;
> > }
> ...
> > -
> > -static void laptop_flush(unsigned long unused)
> > -{
> > - sys_sync();
> > -}
> > -
> > static void laptop_timer_fn(unsigned long unused)
> > {
> > - pdflush_operation(laptop_flush, 0);
> > + wakeup_flusher_threads(0);
> > }
> >
> > /*
> Here you significantly change the behavior of laptop mode - previously it
> reliably synced all the data to disk once the "laptop writeout timeout"
> elapsed. The idea is that we want to write all the dirty data we have so
> that the drive can go to sleep for a longer period.
Yeah I know, I wrote the original laptop mode implementation :-)
> Now you changed that to asynchronous WB_SYNC_NONE writeback of some
> number of pages. In particular if the disk gets congested, we'll just stop
> doing writeback which probably isn't what we want for laptop mode...
Congestion doesn't matter, we don't do nonblocking writeout from the
threads at all. And it is sync later in the series.
I'll switch it back to async in general throughout the series, and add
some way of making sure we actually have things submitted before doing
the filemap_fdatawait() in generic_sync_sb_inodes(). I think that should
fix it.
--
Jens Axboe
^ permalink raw reply [flat|nested] 27+ messages in thread
* Re: [PATCH 06/12] writeback: separate the flushing state/task from the bdi
2009-05-25 10:13 ` Jan Kara
@ 2009-05-25 10:36 ` Jens Axboe
0 siblings, 0 replies; 27+ messages in thread
From: Jens Axboe @ 2009-05-25 10:36 UTC (permalink / raw)
To: Jan Kara
Cc: linux-kernel, linux-fsdevel, chris.mason, david, hch, akpm, yanmin_zhang
On Mon, May 25 2009, Jan Kara wrote:
> On Mon 25-05-09 09:34:41, Jens Axboe wrote:
> > Add a struct bdi_writeback for tracking and handling dirty IO. This
> > is in preparation for adding > 1 flusher task per bdi.
> >
> > Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
> ...
> > static int bdi_start_fn(void *ptr)
> > {
> > - struct backing_dev_info *bdi = ptr;
> > + struct bdi_writeback *wb = ptr;
> > + struct backing_dev_info *bdi = wb->bdi;
> > struct task_struct *tsk = current;
> > -
> > - /*
> > - * Add us to the active bdi_list
> > - */
> > - mutex_lock(&bdi_lock);
> > - list_add(&bdi->bdi_list, &bdi_list);
> > - mutex_unlock(&bdi_lock);
> I'm probably missing something but I cannot find where the bdi is added
> to the bdi_list after this patch...
For some reason, that part is now in the following patch. The two hunks
should just be deleted, good catch!
--
Jens Axboe
^ permalink raw reply [flat|nested] 27+ messages in thread
* Re: [PATCH 04/12] writeback: switch to per-bdi threads for flushing data
2009-05-25 10:34 ` Jens Axboe
@ 2009-05-25 12:10 ` Jan Kara
2009-05-25 12:16 ` Jens Axboe
0 siblings, 1 reply; 27+ messages in thread
From: Jan Kara @ 2009-05-25 12:10 UTC (permalink / raw)
To: Jens Axboe
Cc: Jan Kara, linux-kernel, linux-fsdevel, chris.mason, david, hch,
akpm, yanmin_zhang
On Mon 25-05-09 12:34:10, Jens Axboe wrote:
> On Mon, May 25 2009, Jan Kara wrote:
> > Hi Jens,
> >
> > I've noticed a few more things:
> >
> > On Mon 25-05-09 09:34:39, Jens Axboe wrote:
> > > diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
> > > index 1137408..7cb4d02 100644
> > > --- a/fs/fs-writeback.c
> > > +++ b/fs/fs-writeback.c
> > > @@ -19,6 +19,8 @@
> > > #include <linux/sched.h>
> > > #include <linux/fs.h>
> > > #include <linux/mm.h>
> > > +#include <linux/kthread.h>
> > > +#include <linux/freezer.h>
> > > #include <linux/writeback.h>
> > > #include <linux/blkdev.h>
> > > #include <linux/backing-dev.h>
> > > @@ -61,10 +63,193 @@ int writeback_in_progress(struct backing_dev_info *bdi)
> > > */
> > > static void writeback_release(struct backing_dev_info *bdi)
> > > {
> > > - BUG_ON(!writeback_in_progress(bdi));
> > > + WARN_ON_ONCE(!writeback_in_progress(bdi));
> > > + bdi->wb_arg.nr_pages = 0;
> > > + bdi->wb_arg.sb = NULL;
> > > clear_bit(BDI_pdflush, &bdi->state);
> > > }
> > >
> > > +int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
> > > + long nr_pages, enum writeback_sync_modes sync_mode)
> > > +{
> > > + /*
> > > + * This only happens the first time someone kicks this bdi, so put
> > > + * it out-of-line.
> > > + */
> > > + if (unlikely(!bdi->task)) {
> > > + bdi_add_default_flusher_task(bdi);
> > > + return 1;
> > > + }
> > > +
> > > + if (writeback_acquire(bdi)) {
> > > + bdi->wb_arg.nr_pages = nr_pages;
> > > + bdi->wb_arg.sb = sb;
> > > + bdi->wb_arg.sync_mode = sync_mode;
> > > + /*
> > > + * make above store seen before the task is woken
> > > + */
> > > + smp_mb();
> > > + wake_up(&bdi->wait);
> > > + }
> > Hmm, wouldn't the interface be more useful if we could just pass down the
> > whole writeback_control to the flusher threads?
>
> Yeah, that's what the later patch does too, when support for > 1 thread
> has been added.
Really? I cannot see it in the series. I see that later you introduce
struct bdi_work but it still contains just nr_pages, sb_data and sync_mode.
What I meant was we could include 'struct writeback_control' into the bdi
(or bdi_work later) and just pass it down so that caller can have more
finegrained control of what writeback the thread is going to perform
(like nonblocking, older_than_this, maybe something else).
> > Maybe a real question is, what should be the role of flusher threads?
> > Should they be just threads for kupdate / pdflush style writeout or do we
> > expect them to be used also for other cases when we need to submit IO to
> > the BDI?
>
> The thought has occured to me to punt other types of work to these
> threads, now that we have them available. I haven't really thought that
> through yet (and other changes may be required too), but it could be
> things like async IO or even simple things like the unplugging that is
> now done by kblockd.
OK.
> > > +
> > > + oldest_jif = jiffies - msecs_to_jiffies(dirty_expire_interval * 10);
> > > +
> > > + nr_to_write = global_page_state(NR_FILE_DIRTY) +
> > > + global_page_state(NR_UNSTABLE_NFS) +
> > > + (inodes_stat.nr_inodes - inodes_stat.nr_unused);
> > > +
> > > + while (nr_to_write > 0) {
> > > + wbc.more_io = 0;
> > > + wbc.encountered_congestion = 0;
> > > + wbc.nr_to_write = MAX_WRITEBACK_PAGES;
> > > + generic_sync_bdi_inodes(NULL, &wbc);
> > > + if (wbc.nr_to_write > 0)
> > > + break; /* All the old data is written */
> > > + nr_to_write -= MAX_WRITEBACK_PAGES;
> > > + }
> > > +}
> > > +
> > > +static inline bool over_bground_thresh(void)
> > > +{
> > > + unsigned long background_thresh, dirty_thresh;
> > > +
> > > + get_dirty_limits(&background_thresh, &dirty_thresh, NULL, NULL);
> > > +
> > > + return (global_page_state(NR_FILE_DIRTY) +
> > > + global_page_state(NR_UNSTABLE_NFS) >= background_thresh);
> > > +}
> > > +
> > > +static void bdi_pdflush(struct backing_dev_info *bdi)
> > > +{
> > > + struct writeback_control wbc = {
> > > + .bdi = bdi,
> > > + .sync_mode = bdi->wb_arg.sync_mode,
> > > + .older_than_this = NULL,
> > > + .range_cyclic = 1,
> > > + };
> > > + long nr_pages = bdi->wb_arg.nr_pages;
> > > +
> > > + for (;;) {
> > > + if (wbc.sync_mode == WB_SYNC_NONE && nr_pages <= 0 &&
> > > + !over_bground_thresh())
> > > + break;
> > > +
> > > + wbc.more_io = 0;
> > > + wbc.encountered_congestion = 0;
> > > + wbc.nr_to_write = MAX_WRITEBACK_PAGES;
> > > + wbc.pages_skipped = 0;
> > > + generic_sync_bdi_inodes(bdi->wb_arg.sb, &wbc);
> > > + nr_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
> > > + /*
> > > + * If we ran out of stuff to write, bail unless more_io got set
> > > + */
> > > + if (wbc.nr_to_write > 0 || wbc.pages_skipped > 0) {
> > > + if (wbc.more_io)
> > > + continue;
> > > + break;
> > > + }
> > > + }
> > > +}
> > > +
> > > +/*
> > > + * Handle writeback of dirty data for the device backed by this bdi. Also
> > > + * wakes up periodically and does kupdated style flushing.
> > > + */
> > > +int bdi_writeback_task(struct backing_dev_info *bdi)
> > > +{
> > > + while (!kthread_should_stop()) {
> > > + unsigned long wait_jiffies;
> > > + DEFINE_WAIT(wait);
> > > +
> > > + prepare_to_wait(&bdi->wait, &wait, TASK_INTERRUPTIBLE);
> > > + wait_jiffies = msecs_to_jiffies(dirty_writeback_interval * 10);
> > > + schedule_timeout(wait_jiffies);
> > > + try_to_freeze();
> > > +
> > > + /*
> > > + * We get here in two cases:
> > > + *
> > > + * schedule_timeout() returned because the dirty writeback
> > > + * interval has elapsed. If that happens, we will be able
> > > + * to acquire the writeback lock and will proceed to do
> > > + * kupdated style writeout.
> > > + *
> > > + * Someone called bdi_start_writeback(), which will acquire
> > > + * the writeback lock. This means our writeback_acquire()
> > > + * below will fail and we call into bdi_pdflush() for
> > > + * pdflush style writeout.
> > > + *
> > > + */
> > > + if (writeback_acquire(bdi))
> > > + bdi_kupdated(bdi);
> > > + else
> > > + bdi_pdflush(bdi);
> > > +
> > > + writeback_release(bdi);
> > > + finish_wait(&bdi->wait, &wait);
> > > + }
> > Hmm, what does protect this thread from racing with umount? Note that old
> > flusher threads took s_umount semaphore and also elevated sb->s_count.
> > If everything is fine, we should have a comment somewhere around here what
> > stops umount from removing things under us or why it does not matter...
> > Maybe this is the reason of the oopses Yanmin saw.
>
> I think it was that oops, it got fixed by generic_sync_sb_inodes() doing
> sync writeout again. So I think what happened is that it closed that
> hole, but there could still be trouble. I'll look into that as well.
>
> > BTW, one more difference here: Previously, if pdflush saw congestion on
> > the device, it did congestion_wait() and retried. Now it end's up waiting
> > whole dirty_writeback_interval so it should result in a bursty writeback on
> > a slow disk, couldn't it?
>
> Now it'll block on the queue instead of giving up, so in my opinion that
> should provide smoother writeout. From the tests I did, it does.
Ah, OK, you don't set wbc->nonblocking from kupdate or pdflush. Makes
sence.
> > > +void bdi_writeback_all(struct super_block *sb, long nr_pages,
> > > + enum writeback_sync_modes sync_mode)
> > > +{
> > > + struct backing_dev_info *bdi, *tmp;
> > > +
> > > + mutex_lock(&bdi_lock);
> > > +
> > > + list_for_each_entry_safe(bdi, tmp, &bdi_list, bdi_list) {
> > > + if (!bdi_has_dirty_io(bdi))
> > > + continue;
> > > + bdi_start_writeback(bdi, sb, nr_pages, sync_mode);
> > > + }
> > > +
> > > + mutex_unlock(&bdi_lock);
> > > +}
> > > +
> > > /**
> > > * __mark_inode_dirty - internal function
> > > * @inode: inode to mark
> > ...
> > > @@ -591,13 +718,10 @@ static void generic_sync_bdi_inodes(struct backing_dev_info *bdi,
> > > void generic_sync_sb_inodes(struct super_block *sb,
> > > struct writeback_control *wbc)
> > > {
> > > - const int is_blkdev_sb = sb_is_blkdev_sb(sb);
> > > - struct backing_dev_info *bdi;
> > > -
> > > - mutex_lock(&bdi_lock);
> > > - list_for_each_entry(bdi, &bdi_list, bdi_list)
> > > - generic_sync_bdi_inodes(bdi, wbc, sb, is_blkdev_sb);
> > > - mutex_unlock(&bdi_lock);
> > > + if (wbc->bdi)
> > > + generic_sync_bdi_inodes(sb, wbc);
> > > + else
> > > + bdi_writeback_all(sb, wbc->nr_to_write, wbc->sync_mode);
> > Hmm, you write in the changelog that bdi_writeback_all() writes inline
> > now but AFAICS it still happens through the writeback threads. Which, on a
> > second though probably *is* what we want because we want writeback to go in
> > parallel on all devices we have.
>
> Note that this is patch 4, later it is sync. But yes, I think it should
Ah, right. I missed that.
> be async as well, but we do need a way to wait on the submitted work to
> be processed in case of WB_SYNC_ALL.
Yes, this is a bit complicated. You'd need some notification bdi_work is
processed.
> > > * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back
> > > * the whole world. Returns 0 if a pdflush thread was dispatched. Returns
> > > * -1 if all pdflush threads were busy.
> > > */
> > > -int wakeup_pdflush(long nr_pages)
> > > +void wakeup_flusher_threads(long nr_pages)
> > > {
> > > if (nr_pages == 0)
> > > nr_pages = global_page_state(NR_FILE_DIRTY) +
> > > global_page_state(NR_UNSTABLE_NFS);
> > > - return pdflush_operation(background_writeout, nr_pages);
> > > + bdi_writeback_all(NULL, nr_pages, WB_SYNC_NONE);
> > > + return;
> > > }
> > ...
> > > -
> > > -static void laptop_flush(unsigned long unused)
> > > -{
> > > - sys_sync();
> > > -}
> > > -
> > > static void laptop_timer_fn(unsigned long unused)
> > > {
> > > - pdflush_operation(laptop_flush, 0);
> > > + wakeup_flusher_threads(0);
> > > }
> > >
> > > /*
> > Here you significantly change the behavior of laptop mode - previously it
> > reliably synced all the data to disk once the "laptop writeout timeout"
> > elapsed. The idea is that we want to write all the dirty data we have so
> > that the drive can go to sleep for a longer period.
> Yeah I know, I wrote the original laptop mode implementation :-)
Sorry, I wasn't aware of that.
> > Now you changed that to asynchronous WB_SYNC_NONE writeback of some
> > number of pages. In particular if the disk gets congested, we'll just stop
> > doing writeback which probably isn't what we want for laptop mode...
>
> Congestion doesn't matter, we don't do nonblocking writeout from the
> threads at all. And it is sync later in the series.
>
> I'll switch it back to async in general throughout the series, and add
> some way of making sure we actually have things submitted before doing
> the filemap_fdatawait() in generic_sync_sb_inodes(). I think that should
> fix it.
OK, looking forward to your patches :)
Honza
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
^ permalink raw reply [flat|nested] 27+ messages in thread
* Re: [PATCH 04/12] writeback: switch to per-bdi threads for flushing data
2009-05-25 12:10 ` Jan Kara
@ 2009-05-25 12:16 ` Jens Axboe
2009-05-25 12:34 ` Jan Kara
0 siblings, 1 reply; 27+ messages in thread
From: Jens Axboe @ 2009-05-25 12:16 UTC (permalink / raw)
To: Jan Kara
Cc: linux-kernel, linux-fsdevel, chris.mason, david, hch, akpm, yanmin_zhang
On Mon, May 25 2009, Jan Kara wrote:
> On Mon 25-05-09 12:34:10, Jens Axboe wrote:
> > On Mon, May 25 2009, Jan Kara wrote:
> > > Hi Jens,
> > >
> > > I've noticed a few more things:
> > >
> > > On Mon 25-05-09 09:34:39, Jens Axboe wrote:
> > > > diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
> > > > index 1137408..7cb4d02 100644
> > > > --- a/fs/fs-writeback.c
> > > > +++ b/fs/fs-writeback.c
> > > > @@ -19,6 +19,8 @@
> > > > #include <linux/sched.h>
> > > > #include <linux/fs.h>
> > > > #include <linux/mm.h>
> > > > +#include <linux/kthread.h>
> > > > +#include <linux/freezer.h>
> > > > #include <linux/writeback.h>
> > > > #include <linux/blkdev.h>
> > > > #include <linux/backing-dev.h>
> > > > @@ -61,10 +63,193 @@ int writeback_in_progress(struct backing_dev_info *bdi)
> > > > */
> > > > static void writeback_release(struct backing_dev_info *bdi)
> > > > {
> > > > - BUG_ON(!writeback_in_progress(bdi));
> > > > + WARN_ON_ONCE(!writeback_in_progress(bdi));
> > > > + bdi->wb_arg.nr_pages = 0;
> > > > + bdi->wb_arg.sb = NULL;
> > > > clear_bit(BDI_pdflush, &bdi->state);
> > > > }
> > > >
> > > > +int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
> > > > + long nr_pages, enum writeback_sync_modes sync_mode)
> > > > +{
> > > > + /*
> > > > + * This only happens the first time someone kicks this bdi, so put
> > > > + * it out-of-line.
> > > > + */
> > > > + if (unlikely(!bdi->task)) {
> > > > + bdi_add_default_flusher_task(bdi);
> > > > + return 1;
> > > > + }
> > > > +
> > > > + if (writeback_acquire(bdi)) {
> > > > + bdi->wb_arg.nr_pages = nr_pages;
> > > > + bdi->wb_arg.sb = sb;
> > > > + bdi->wb_arg.sync_mode = sync_mode;
> > > > + /*
> > > > + * make above store seen before the task is woken
> > > > + */
> > > > + smp_mb();
> > > > + wake_up(&bdi->wait);
> > > > + }
> > > Hmm, wouldn't the interface be more useful if we could just pass down the
> > > whole writeback_control to the flusher threads?
> >
> > Yeah, that's what the later patch does too, when support for > 1 thread
> > has been added.
> Really? I cannot see it in the series. I see that later you introduce
> struct bdi_work but it still contains just nr_pages, sb_data and sync_mode.
> What I meant was we could include 'struct writeback_control' into the bdi
> (or bdi_work later) and just pass it down so that caller can have more
> finegrained control of what writeback the thread is going to perform
> (like nonblocking, older_than_this, maybe something else).
Oh, I don't pass wbc down, but I do pass it async. The problem with
passing down the wbc is that it is allocated on the stack. So if we do
that, then we pretty much have to serialize on that. And I want to avoid
that.
> > > > void generic_sync_sb_inodes(struct super_block *sb,
> > > > struct writeback_control *wbc)
> > > > {
> > > > - const int is_blkdev_sb = sb_is_blkdev_sb(sb);
> > > > - struct backing_dev_info *bdi;
> > > > -
> > > > - mutex_lock(&bdi_lock);
> > > > - list_for_each_entry(bdi, &bdi_list, bdi_list)
> > > > - generic_sync_bdi_inodes(bdi, wbc, sb, is_blkdev_sb);
> > > > - mutex_unlock(&bdi_lock);
> > > > + if (wbc->bdi)
> > > > + generic_sync_bdi_inodes(sb, wbc);
> > > > + else
> > > > + bdi_writeback_all(sb, wbc->nr_to_write, wbc->sync_mode);
> > > Hmm, you write in the changelog that bdi_writeback_all() writes inline
> > > now but AFAICS it still happens through the writeback threads. Which, on a
> > > second though probably *is* what we want because we want writeback to go in
> > > parallel on all devices we have.
> >
> > Note that this is patch 4, later it is sync. But yes, I think it should
> Ah, right. I missed that.
>
> > be async as well, but we do need a way to wait on the submitted work to
> > be processed in case of WB_SYNC_ALL.
> Yes, this is a bit complicated. You'd need some notification bdi_work is
> processed.
It was actually not that hard, I already did it. So right now
wb_writeback() does this:
while (work) {
get args;
clear pending;
do work;
};
If we just modify that to:
while (work) {
get args;
if (sync_mode == WB_SYNC_NONE)
clear pending;
do work;
if (sync_mode == WB_SYNC_ALL)
clear_pending;
};
We get notification when the work has actually been issued. Then we can
easily control whether or not to make a piece of work sync or not.
> > > > * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back
> > > > * the whole world. Returns 0 if a pdflush thread was dispatched. Returns
> > > > * -1 if all pdflush threads were busy.
> > > > */
> > > > -int wakeup_pdflush(long nr_pages)
> > > > +void wakeup_flusher_threads(long nr_pages)
> > > > {
> > > > if (nr_pages == 0)
> > > > nr_pages = global_page_state(NR_FILE_DIRTY) +
> > > > global_page_state(NR_UNSTABLE_NFS);
> > > > - return pdflush_operation(background_writeout, nr_pages);
> > > > + bdi_writeback_all(NULL, nr_pages, WB_SYNC_NONE);
> > > > + return;
> > > > }
> > > ...
> > > > -
> > > > -static void laptop_flush(unsigned long unused)
> > > > -{
> > > > - sys_sync();
> > > > -}
> > > > -
> > > > static void laptop_timer_fn(unsigned long unused)
> > > > {
> > > > - pdflush_operation(laptop_flush, 0);
> > > > + wakeup_flusher_threads(0);
> > > > }
> > > >
> > > > /*
> > > Here you significantly change the behavior of laptop mode - previously it
> > > reliably synced all the data to disk once the "laptop writeout timeout"
> > > elapsed. The idea is that we want to write all the dirty data we have so
> > > that the drive can go to sleep for a longer period.
> > Yeah I know, I wrote the original laptop mode implementation :-)
> Sorry, I wasn't aware of that.
>
> > > Now you changed that to asynchronous WB_SYNC_NONE writeback of some
> > > number of pages. In particular if the disk gets congested, we'll just stop
> > > doing writeback which probably isn't what we want for laptop mode...
> >
> > Congestion doesn't matter, we don't do nonblocking writeout from the
> > threads at all. And it is sync later in the series.
> >
> > I'll switch it back to async in general throughout the series, and add
> > some way of making sure we actually have things submitted before doing
> > the filemap_fdatawait() in generic_sync_sb_inodes(). I think that should
> > fix it.
> OK, looking forward to your patches :)
Fiddling with it now, probably a v7 posting coming up tomorrow. And
thanks again for your great and detailed reviews!
--
Jens Axboe
^ permalink raw reply [flat|nested] 27+ messages in thread
* Re: [PATCH 04/12] writeback: switch to per-bdi threads for flushing data
2009-05-25 12:16 ` Jens Axboe
@ 2009-05-25 12:34 ` Jan Kara
0 siblings, 0 replies; 27+ messages in thread
From: Jan Kara @ 2009-05-25 12:34 UTC (permalink / raw)
To: Jens Axboe
Cc: linux-kernel, linux-fsdevel, chris.mason, david, hch, akpm, yanmin_zhang
On Mon 25-05-09 14:16:48, Jens Axboe wrote:
> On Mon, May 25 2009, Jan Kara wrote:
> > On Mon 25-05-09 12:34:10, Jens Axboe wrote:
> > > On Mon, May 25 2009, Jan Kara wrote:
> > > > Hi Jens,
> > > >
> > > > I've noticed a few more things:
> > > >
> > > > On Mon 25-05-09 09:34:39, Jens Axboe wrote:
> > > > > diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
> > > > > index 1137408..7cb4d02 100644
> > > > > --- a/fs/fs-writeback.c
> > > > > +++ b/fs/fs-writeback.c
> > > > > @@ -19,6 +19,8 @@
> > > > > #include <linux/sched.h>
> > > > > #include <linux/fs.h>
> > > > > #include <linux/mm.h>
> > > > > +#include <linux/kthread.h>
> > > > > +#include <linux/freezer.h>
> > > > > #include <linux/writeback.h>
> > > > > #include <linux/blkdev.h>
> > > > > #include <linux/backing-dev.h>
> > > > > @@ -61,10 +63,193 @@ int writeback_in_progress(struct backing_dev_info *bdi)
> > > > > */
> > > > > static void writeback_release(struct backing_dev_info *bdi)
> > > > > {
> > > > > - BUG_ON(!writeback_in_progress(bdi));
> > > > > + WARN_ON_ONCE(!writeback_in_progress(bdi));
> > > > > + bdi->wb_arg.nr_pages = 0;
> > > > > + bdi->wb_arg.sb = NULL;
> > > > > clear_bit(BDI_pdflush, &bdi->state);
> > > > > }
> > > > >
> > > > > +int bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
> > > > > + long nr_pages, enum writeback_sync_modes sync_mode)
> > > > > +{
> > > > > + /*
> > > > > + * This only happens the first time someone kicks this bdi, so put
> > > > > + * it out-of-line.
> > > > > + */
> > > > > + if (unlikely(!bdi->task)) {
> > > > > + bdi_add_default_flusher_task(bdi);
> > > > > + return 1;
> > > > > + }
> > > > > +
> > > > > + if (writeback_acquire(bdi)) {
> > > > > + bdi->wb_arg.nr_pages = nr_pages;
> > > > > + bdi->wb_arg.sb = sb;
> > > > > + bdi->wb_arg.sync_mode = sync_mode;
> > > > > + /*
> > > > > + * make above store seen before the task is woken
> > > > > + */
> > > > > + smp_mb();
> > > > > + wake_up(&bdi->wait);
> > > > > + }
> > > > Hmm, wouldn't the interface be more useful if we could just pass down the
> > > > whole writeback_control to the flusher threads?
> > >
> > > Yeah, that's what the later patch does too, when support for > 1 thread
> > > has been added.
> > Really? I cannot see it in the series. I see that later you introduce
> > struct bdi_work but it still contains just nr_pages, sb_data and sync_mode.
> > What I meant was we could include 'struct writeback_control' into the bdi
> > (or bdi_work later) and just pass it down so that caller can have more
> > finegrained control of what writeback the thread is going to perform
> > (like nonblocking, older_than_this, maybe something else).
>
> Oh, I don't pass wbc down, but I do pass it async. The problem with
> passing down the wbc is that it is allocated on the stack. So if we do
> that, then we pretty much have to serialize on that. And I want to avoid
> that.
I see. OK, let's leave it as it is for now. If we find it's really needed,
we should be able to handle this later (by copying the structure from the
stack into dynamically allocated memory or so).
> > > > > void generic_sync_sb_inodes(struct super_block *sb,
> > > > > struct writeback_control *wbc)
> > > > > {
> > > > > - const int is_blkdev_sb = sb_is_blkdev_sb(sb);
> > > > > - struct backing_dev_info *bdi;
> > > > > -
> > > > > - mutex_lock(&bdi_lock);
> > > > > - list_for_each_entry(bdi, &bdi_list, bdi_list)
> > > > > - generic_sync_bdi_inodes(bdi, wbc, sb, is_blkdev_sb);
> > > > > - mutex_unlock(&bdi_lock);
> > > > > + if (wbc->bdi)
> > > > > + generic_sync_bdi_inodes(sb, wbc);
> > > > > + else
> > > > > + bdi_writeback_all(sb, wbc->nr_to_write, wbc->sync_mode);
> > > > Hmm, you write in the changelog that bdi_writeback_all() writes inline
> > > > now but AFAICS it still happens through the writeback threads. Which, on a
> > > > second though probably *is* what we want because we want writeback to go in
> > > > parallel on all devices we have.
> > >
> > > Note that this is patch 4, later it is sync. But yes, I think it should
> > Ah, right. I missed that.
> >
> > > be async as well, but we do need a way to wait on the submitted work to
> > > be processed in case of WB_SYNC_ALL.
> > Yes, this is a bit complicated. You'd need some notification bdi_work is
> > processed.
>
> It was actually not that hard, I already did it. So right now
> wb_writeback() does this:
>
> while (work) {
> get args;
> clear pending;
> do work;
> };
>
> If we just modify that to:
>
> while (work) {
> get args;
> if (sync_mode == WB_SYNC_NONE)
> clear pending;
> do work;
> if (sync_mode == WB_SYNC_ALL)
> clear_pending;
> };
>
> We get notification when the work has actually been issued. Then we can
> easily control whether or not to make a piece of work sync or not.
OK. That should work.
> > > > > * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back
> > > > > * the whole world. Returns 0 if a pdflush thread was dispatched. Returns
> > > > > * -1 if all pdflush threads were busy.
> > > > > */
> > > > > -int wakeup_pdflush(long nr_pages)
> > > > > +void wakeup_flusher_threads(long nr_pages)
> > > > > {
> > > > > if (nr_pages == 0)
> > > > > nr_pages = global_page_state(NR_FILE_DIRTY) +
> > > > > global_page_state(NR_UNSTABLE_NFS);
> > > > > - return pdflush_operation(background_writeout, nr_pages);
> > > > > + bdi_writeback_all(NULL, nr_pages, WB_SYNC_NONE);
> > > > > + return;
> > > > > }
> > > > ...
> > > > > -
> > > > > -static void laptop_flush(unsigned long unused)
> > > > > -{
> > > > > - sys_sync();
> > > > > -}
> > > > > -
> > > > > static void laptop_timer_fn(unsigned long unused)
> > > > > {
> > > > > - pdflush_operation(laptop_flush, 0);
> > > > > + wakeup_flusher_threads(0);
> > > > > }
> > > > >
> > > > > /*
> > > > Here you significantly change the behavior of laptop mode - previously it
> > > > reliably synced all the data to disk once the "laptop writeout timeout"
> > > > elapsed. The idea is that we want to write all the dirty data we have so
> > > > that the drive can go to sleep for a longer period.
> > > Yeah I know, I wrote the original laptop mode implementation :-)
> > Sorry, I wasn't aware of that.
> >
> > > > Now you changed that to asynchronous WB_SYNC_NONE writeback of some
> > > > number of pages. In particular if the disk gets congested, we'll just stop
> > > > doing writeback which probably isn't what we want for laptop mode...
> > >
> > > Congestion doesn't matter, we don't do nonblocking writeout from the
> > > threads at all. And it is sync later in the series.
> > >
> > > I'll switch it back to async in general throughout the series, and add
> > > some way of making sure we actually have things submitted before doing
> > > the filemap_fdatawait() in generic_sync_sb_inodes(). I think that should
> > > fix it.
> > OK, looking forward to your patches :)
>
> Fiddling with it now, probably a v7 posting coming up tomorrow. And
> thanks again for your great and detailed reviews!
Honza
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
^ permalink raw reply [flat|nested] 27+ messages in thread
* Re: [PATCH 04/12] writeback: switch to per-bdi threads for flushing data
2009-05-25 9:58 ` Jan Kara
2009-05-25 10:34 ` Jens Axboe
@ 2009-05-26 8:56 ` Jens Axboe
2009-05-26 8:59 ` Christoph Hellwig
1 sibling, 1 reply; 27+ messages in thread
From: Jens Axboe @ 2009-05-26 8:56 UTC (permalink / raw)
To: Jan Kara
Cc: linux-kernel, linux-fsdevel, chris.mason, david, hch, akpm, yanmin_zhang
On Mon, May 25 2009, Jan Kara wrote:
> > +static void bdi_kupdated(struct backing_dev_info *bdi)
> > +{
> > + unsigned long oldest_jif;
> > + long nr_to_write;
> > + struct writeback_control wbc = {
> > + .bdi = bdi,
> > + .sync_mode = WB_SYNC_NONE,
> > + .older_than_this = &oldest_jif,
> > + .nr_to_write = 0,
> > + .for_kupdate = 1,
> > + .range_cyclic = 1,
> > + };
> > +
> > + sync_supers();
> Hmm, so each BDI flusher thread is going to sync all the superblocks?
> Isn't there a better way? I suppose we *should* be able to somehow go
> from a BDI to a superblock (or maybe a list of those) so that we can write
> per-fs metadata not bound to inodes.
I just moved the sync_supers() to the bdi_forker_task(). That makes it
global at the same interval of wakeups, instead of doing in the bdi
threads. It would be nice to sync locally instead, but that's something
that can wait for later (if ever).
--
Jens Axboe
^ permalink raw reply [flat|nested] 27+ messages in thread
* Re: [PATCH 04/12] writeback: switch to per-bdi threads for flushing data
2009-05-26 8:56 ` Jens Axboe
@ 2009-05-26 8:59 ` Christoph Hellwig
2009-05-26 9:07 ` Jens Axboe
0 siblings, 1 reply; 27+ messages in thread
From: Christoph Hellwig @ 2009-05-26 8:59 UTC (permalink / raw)
To: Jens Axboe
Cc: Jan Kara, linux-kernel, linux-fsdevel, chris.mason, david, hch,
akpm, yanmin_zhang
On Tue, May 26, 2009 at 10:56:48AM +0200, Jens Axboe wrote:
> > Hmm, so each BDI flusher thread is going to sync all the superblocks?
> > Isn't there a better way? I suppose we *should* be able to somehow go
> > from a BDI to a superblock (or maybe a list of those) so that we can write
> > per-fs metadata not bound to inodes.
>
> I just moved the sync_supers() to the bdi_forker_task(). That makes it
> global at the same interval of wakeups, instead of doing in the bdi
> threads. It would be nice to sync locally instead, but that's something
> that can wait for later (if ever).
For now it might be easier to just have a separate thread for calling
sync_supers instead of interwinding it with the data writeback.
Btw, XFS currently has a per-device thread for that, to avoid any global
contention.
^ permalink raw reply [flat|nested] 27+ messages in thread
* Re: [PATCH 04/12] writeback: switch to per-bdi threads for flushing data
2009-05-26 8:59 ` Christoph Hellwig
@ 2009-05-26 9:07 ` Jens Axboe
0 siblings, 0 replies; 27+ messages in thread
From: Jens Axboe @ 2009-05-26 9:07 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Jan Kara, linux-kernel, linux-fsdevel, chris.mason, david, akpm,
yanmin_zhang
On Tue, May 26 2009, Christoph Hellwig wrote:
> On Tue, May 26, 2009 at 10:56:48AM +0200, Jens Axboe wrote:
> > > Hmm, so each BDI flusher thread is going to sync all the superblocks?
> > > Isn't there a better way? I suppose we *should* be able to somehow go
> > > from a BDI to a superblock (or maybe a list of those) so that we can write
> > > per-fs metadata not bound to inodes.
> >
> > I just moved the sync_supers() to the bdi_forker_task(). That makes it
> > global at the same interval of wakeups, instead of doing in the bdi
> > threads. It would be nice to sync locally instead, but that's something
> > that can wait for later (if ever).
>
> For now it might be easier to just have a separate thread for calling
> sync_supers instead of interwinding it with the data writeback.
>
> Btw, XFS currently has a per-device thread for that, to avoid any global
> contention.
That's basically what the mentioned change does. bdi_forker_task() is a
the default_backing_dev task, it does little more than simply setup new
threads and such.
--
Jens Axboe
^ permalink raw reply [flat|nested] 27+ messages in thread
* [PATCH 08/12] writeback: include default_backing_dev_info in writeback
2009-05-26 9:33 [PATCH 0/12] Per-bdi writeback flusher threads v7 Jens Axboe
@ 2009-05-26 9:33 ` Jens Axboe
0 siblings, 0 replies; 27+ messages in thread
From: Jens Axboe @ 2009-05-26 9:33 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, hch, akpm, jack, yanmin_zhang, richard, Jens Axboe
We see dirty inodes there occasionally, so better be safe and write them
out.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
fs/fs-writeback.c | 2 +-
include/linux/writeback.h | 1 +
mm/backing-dev.c | 8 ++++++--
3 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 8e0902e..e4f96b9 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -432,7 +432,7 @@ static void wb_writeback(struct bdi_writeback *wb)
* This will be inlined in bdi_writeback_task() once we get rid of any
* dirty inodes on the default_backing_dev_info
*/
-static void wb_do_writeback(struct bdi_writeback *wb)
+void wb_do_writeback(struct bdi_writeback *wb)
{
/*
* We get here in two cases:
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index baf04a9..e414702 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -69,6 +69,7 @@ void writeback_inodes(struct writeback_control *wbc);
int inode_wait(void *);
void sync_inodes_sb(struct super_block *, int wait);
void sync_inodes(int wait);
+void wb_do_writeback(struct bdi_writeback *wb);
/* writeback.h requires fs.h; it, too, is not included from here. */
static inline void wait_on_inode(struct inode *inode)
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 57e44e3..977c171 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -396,8 +396,8 @@ static int bdi_forker_task(void *ptr)
* Temporary measure, we want to make sure we don't see
* dirty data on the default backing_dev_info
*/
- if (wb_has_dirty_io(me))
- bdi_flush_io(me->bdi);
+ if (wb_has_dirty_io(me) || !list_empty(&me->bdi->work_list))
+ wb_do_writeback(me);
prepare_to_wait(&me->wait, &wait, TASK_INTERRUPTIBLE);
@@ -424,6 +424,10 @@ static int bdi_forker_task(void *ptr)
continue;
}
+ /*
+ * This is our real job - check for pending entries in
+ * bdi_pending_list, and create the tasks that got added
+ */
bdi = list_entry(bdi_pending_list.next, struct backing_dev_info,
bdi_list);
list_del_init(&bdi->bdi_list);
--
1.6.3.rc0.1.gf800
^ permalink raw reply related [flat|nested] 27+ messages in thread
* [PATCH 08/12] writeback: include default_backing_dev_info in writeback
2009-05-25 7:30 [PATCH 0/12] Per-bdi writeback flusher threads #5 Jens Axboe
@ 2009-05-25 7:30 ` Jens Axboe
0 siblings, 0 replies; 27+ messages in thread
From: Jens Axboe @ 2009-05-25 7:30 UTC (permalink / raw)
To: linux-kernel, linux-fsdevel
Cc: chris.mason, david, hch, akpm, jack, yanmin_zhang, Jens Axboe
We see dirty inodes there occasionally, so better be safe and write them
out.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
fs/fs-writeback.c | 2 +-
include/linux/writeback.h | 1 +
mm/backing-dev.c | 16 +++++++++++-----
3 files changed, 13 insertions(+), 6 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 563860c..47f5ace 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -364,7 +364,7 @@ static void wb_writeback(struct bdi_writeback *wb)
* This will be inlined in bdi_writeback_task() once we get rid of any
* dirty inodes on the default_backing_dev_info
*/
-static void wb_do_writeback(struct bdi_writeback *wb)
+void wb_do_writeback(struct bdi_writeback *wb)
{
/*
* We get here in two cases:
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index baf04a9..e414702 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -69,6 +69,7 @@ void writeback_inodes(struct writeback_control *wbc);
int inode_wait(void *);
void sync_inodes_sb(struct super_block *, int wait);
void sync_inodes(int wait);
+void wb_do_writeback(struct bdi_writeback *wb);
/* writeback.h requires fs.h; it, too, is not included from here. */
static inline void wait_on_inode(struct inode *inode)
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 3e74041..3a032be 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -388,12 +388,14 @@ static int bdi_forker_task(void *ptr)
struct bdi_writeback *wb;
/*
- * Should never trigger on the default bdi
+ * Ideally we'd like not to see any dirty inodes on the
+ * default_backing_dev_info. Until these are tracked down,
+ * perform the same writeback here that bdi_writeback_task
+ * does. For logic, see comment in
+ * fs/fs-writeback.c:bdi_writeback_task()
*/
- if (wb_has_dirty_io(me)) {
- bdi_flush_io(me->bdi);
- WARN_ON(1);
- }
+ if (wb_has_dirty_io(me) || !list_empty(&me->bdi->work_list))
+ wb_do_writeback(me);
prepare_to_wait(&me->wait, &wait, TASK_INTERRUPTIBLE);
@@ -420,6 +422,10 @@ static int bdi_forker_task(void *ptr)
continue;
}
+ /*
+ * This is our real job - check for pending entries in
+ * bdi_pending_list, and create the tasks that got added
+ */
bdi = list_entry(bdi_pending_list.next, struct backing_dev_info,
bdi_list);
list_del_init(&bdi->bdi_list);
--
1.6.3.rc0.1.gf800
^ permalink raw reply related [flat|nested] 27+ messages in thread
end of thread, other threads:[~2009-05-26 9:35 UTC | newest]
Thread overview: 27+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2009-05-25 7:34 [PATCH 0/12] Per-bdi writeback flusher threads #5 Jens Axboe
2009-05-25 7:34 ` [PATCH 01/12] ntfs: remove old debug check for dirty data in ntfs_put_super() Jens Axboe
2009-05-25 7:34 ` [PATCH 02/12] btrfs: properly register fs backing device Jens Axboe
2009-05-25 7:34 ` [PATCH 03/12] writeback: move dirty inodes from super_block to backing_dev_info Jens Axboe
2009-05-25 8:42 ` Jan Kara
2009-05-25 8:51 ` Jens Axboe
2009-05-25 7:34 ` [PATCH 04/12] writeback: switch to per-bdi threads for flushing data Jens Axboe
2009-05-25 9:58 ` Jan Kara
2009-05-25 10:34 ` Jens Axboe
2009-05-25 12:10 ` Jan Kara
2009-05-25 12:16 ` Jens Axboe
2009-05-25 12:34 ` Jan Kara
2009-05-26 8:56 ` Jens Axboe
2009-05-26 8:59 ` Christoph Hellwig
2009-05-26 9:07 ` Jens Axboe
2009-05-25 7:34 ` [PATCH 05/12] writeback: get rid of pdflush completely Jens Axboe
2009-05-25 7:34 ` [PATCH 06/12] writeback: separate the flushing state/task from the bdi Jens Axboe
2009-05-25 10:13 ` Jan Kara
2009-05-25 10:36 ` Jens Axboe
2009-05-25 7:34 ` [PATCH 07/12] writeback: support > 1 flusher thread per bdi Jens Axboe
2009-05-25 7:34 ` [PATCH 08/12] writeback: include default_backing_dev_info in writeback Jens Axboe
2009-05-25 7:34 ` [PATCH 09/12] writeback: allow sleepy exit of default writeback task Jens Axboe
2009-05-25 7:34 ` [PATCH 10/12] writeback: add some debug inode list counters to bdi stats Jens Axboe
2009-05-25 7:34 ` [PATCH 11/12] writeback: add name to backing_dev_info Jens Axboe
2009-05-25 7:34 ` [PATCH 12/12] writeback: check for registered bdi in flusher add and inode dirty Jens Axboe
-- strict thread matches above, loose matches on Subject: below --
2009-05-26 9:33 [PATCH 0/12] Per-bdi writeback flusher threads v7 Jens Axboe
2009-05-26 9:33 ` [PATCH 08/12] writeback: include default_backing_dev_info in writeback Jens Axboe
2009-05-25 7:30 [PATCH 0/12] Per-bdi writeback flusher threads #5 Jens Axboe
2009-05-25 7:30 ` [PATCH 08/12] writeback: include default_backing_dev_info in writeback Jens Axboe
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