[PATCHSET v3] Add support for write life time hints

[PATCHSET v3] Add support for write life time hints

[Jens Axboe]

A new iteration of this patchset, previously known as write streams.
As before, this patchset aims at enabling applications split up
writes into separate streams, based on the perceived life time
of the data written. This is useful for a variety of reasons:

- With NVMe 1.3 compliant devices, the device can expose multiple
  streams. Separating data written into streams based on life time
  can drastically reduce the write amplification. This helps device
  endurance, and increases performance. Testing just performed
  internally at Facebook with these patches showed up to a 25%
  reduction in NAND writes in a RocksDB setup.

- Software caching solutions can make more intelligent decisions
  on how and where to place data.

Contrary to previous patches, we're not exposing numeric stream values anymore.
I've previously advocated for just doing a set of hints that makes sense
instead. See the coverage from the LSFMM summit this year:

https://lwn.net/Articles/717755/

This patchset attempts to do that. We define 4 flags for the pwritev2
system call:

RWF_WRITE_LIFE_SHORT	Data written with this flag is expected to have
			a high overwrite rate, or life time.

RWF_WRITE_LIFE_MEDIUM	Longer life time than SHORT

RWF_WRITE_LIFE_LONG	Longer life time than MEDIUM

RWF_WRITE_LIFE_EXTREME	Longer life time than LONG

The idea is that these are relative values, so an application can
use them as they see fit. The underlying device can then place
data appropriately, or be free to ignore the hint. It's just a hint.

A branch based on current master can be pulled
from here:

git://git.kernel.dk/linux-block write-stream.3

Changes since v2:

- Get rid of bio->bi_stream and replace with four request/bio flags.
  These map directly to the RWF_WRITE_* flags that the user passes in.
- Cleanup the NVMe stream setting.
- Drivers now responsible for updating the queue stream write counter,
  as they determine what stream to map a given flag to.

Changes since v1:

- Guard queue stream stats to ensure we don't mess up memory, if
  bio_stream() ever were to return a larger value than we support.
- NVMe: ensure we set the stream modulo the name space defined count.
- Cleanup the RWF_ and IOCB_ flags. Set aside 4 bits, and just store
  the stream value in there. This makes the passing of stream ID from
  RWF_ space to IOCB_ (and IOCB_ to bio) more efficient, and cleans it
  up in general.
- Kill the block internal definitions of the stream type, we don't need
  them anymore. See above.

-- 
Jens Axboe

[PATCH 01/11] block: add support for carrying stream information in a bio

[Jens Axboe]

No functional changes in this patch, we just add four flags
that will be used to denote a stream type, and ensure that we
don't merge across different stream types.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 block/blk-merge.c         | 16 ++++++++++++++++
 include/linux/blk_types.h | 11 +++++++++++
 2 files changed, 27 insertions(+)

diff --git a/block/blk-merge.c b/block/blk-merge.c
index 3990ae406341..7d299df3b12b 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -693,6 +693,14 @@ static struct request *attempt_merge(struct request_queue *q,
 		return NULL;
 
 	/*
+	 * Don't allow merge of different streams, or for a stream with
+	 * non-stream IO.
+	 */
+	if ((req->cmd_flags & REQ_WRITE_LIFE_MASK) !=
+	    (next->cmd_flags & REQ_WRITE_LIFE_MASK))
+		return NULL;
+
+	/*
 	 * If we are allowed to merge, then append bio list
 	 * from next to rq and release next. merge_requests_fn
 	 * will have updated segment counts, update sector
@@ -811,6 +819,14 @@ bool blk_rq_merge_ok(struct request *rq, struct bio *bio)
 	    !blk_write_same_mergeable(rq->bio, bio))
 		return false;
 
+	/*
+	 * Don't allow merge of different streams, or for a stream with
+	 * non-stream IO.
+	 */
+	if ((rq->cmd_flags & REQ_WRITE_LIFE_MASK) !=
+	    (bio->bi_opf & REQ_WRITE_LIFE_MASK))
+		return false;
+
 	return true;
 }
 
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 61339bc44400..57d1eb530799 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -201,6 +201,10 @@ enum req_flag_bits {
 	__REQ_PREFLUSH,		/* request for cache flush */
 	__REQ_RAHEAD,		/* read ahead, can fail anytime */
 	__REQ_BACKGROUND,	/* background IO */
+	__REQ_WRITE_SHORT,	/* short life time write */
+	__REQ_WRITE_MEDIUM,	/* medium life time write */
+	__REQ_WRITE_LONG,	/* long life time write */
+	__REQ_WRITE_EXTREME,	/* extremely long life time write */
 
 	/* command specific flags for REQ_OP_WRITE_ZEROES: */
 	__REQ_NOUNMAP,		/* do not free blocks when zeroing */
@@ -221,6 +225,13 @@ enum req_flag_bits {
 #define REQ_PREFLUSH		(1ULL << __REQ_PREFLUSH)
 #define REQ_RAHEAD		(1ULL << __REQ_RAHEAD)
 #define REQ_BACKGROUND		(1ULL << __REQ_BACKGROUND)
+#define REQ_WRITE_SHORT		(1ULL << __REQ_WRITE_SHORT)
+#define REQ_WRITE_MEDIUM	(1ULL << __REQ_WRITE_MEDIUM)
+#define REQ_WRITE_LONG		(1ULL << __REQ_WRITE_LONG)
+#define REQ_WRITE_EXTREME	(1ULL << __REQ_WRITE_EXTREME)
+
+#define REQ_WRITE_LIFE_MASK	(REQ_WRITE_SHORT | REQ_WRITE_MEDIUM | \
+					REQ_WRITE_LONG | REQ_WRITE_EXTREME)
 
 #define REQ_NOUNMAP		(1ULL << __REQ_NOUNMAP)
 
-- 
2.7.4

[PATCH 02/11] blk-mq: expose stream write stats through debugfs

[Jens Axboe]

Useful to verify that things are working the way they should.
Reading the file will return number of kb written to each
stream. Writing the file will reset the statistics. No care
is taken to ensure that we don't race on updates.

Drivers will write to q->stream_writes[] if they handle a stream.

Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 block/blk-mq-debugfs.c | 24 ++++++++++++++++++++++++
 include/linux/blkdev.h |  3 +++
 2 files changed, 27 insertions(+)

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 803aed4d7221..0a37c848961d 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -133,6 +133,29 @@ static void print_stat(struct seq_file *m, struct blk_rq_stat *stat)
 	}
 }
 
+static int queue_streams_show(void *data, struct seq_file *m)
+{
+	struct request_queue *q = data;
+	int i;
+
+	for (i = 0; i < BLK_MAX_STREAM; i++)
+		seq_printf(m, "stream%d: %llu\n", i, q->stream_writes[i]);
+
+	return 0;
+}
+
+static ssize_t queue_streams_store(void *data, const char __user *buf,
+				   size_t count, loff_t *ppos)
+{
+	struct request_queue *q = data;
+	int i;
+
+	for (i = 0; i < BLK_MAX_STREAM; i++)
+		q->stream_writes[i] = 0;
+
+	return count;
+}
+
 static int queue_poll_stat_show(void *data, struct seq_file *m)
 {
 	struct request_queue *q = data;
@@ -656,6 +679,7 @@ const struct file_operations blk_mq_debugfs_fops = {
 static const struct blk_mq_debugfs_attr blk_mq_debugfs_queue_attrs[] = {
 	{"poll_stat", 0400, queue_poll_stat_show},
 	{"state", 0600, queue_state_show, queue_state_write},
+	{"streams", 0600, queue_streams_show, queue_streams_store},
 	{},
 };
 
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index ab92c4ea138b..88719c6f3edf 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -586,6 +586,9 @@ struct request_queue {
 
 	size_t			cmd_size;
 	void			*rq_alloc_data;
+
+#define BLK_MAX_STREAM	5
+	u64			stream_writes[BLK_MAX_STREAM];
 };
 
 #define QUEUE_FLAG_QUEUED	1	/* uses generic tag queueing */
-- 
2.7.4

[PATCH 03/11] fs: add support for an inode to carry stream related data

[Jens Axboe]

No functional changes in this patch, just in preparation for
allowing applications to pass in hints about data life times
for writes.

Pack the i_stream field into a 2-byte hole, so we don't grow
the size of the inode.

Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/inode.c         | 1 +
 include/linux/fs.h | 9 +++++++++
 2 files changed, 10 insertions(+)

diff --git a/fs/inode.c b/fs/inode.c
index db5914783a71..5717cb378fda 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -149,6 +149,7 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
 	inode->i_blocks = 0;
 	inode->i_bytes = 0;
 	inode->i_generation = 0;
+	inode->i_stream = 0;
 	inode->i_pipe = NULL;
 	inode->i_bdev = NULL;
 	inode->i_cdev = NULL;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 803e5a9b2654..771e172d23d7 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -591,6 +591,7 @@ struct inode {
 	struct timespec		i_ctime;
 	spinlock_t		i_lock;	/* i_blocks, i_bytes, maybe i_size */
 	unsigned short          i_bytes;
+	unsigned short		i_stream;
 	unsigned int		i_blkbits;
 	blkcnt_t		i_blocks;
 
@@ -655,6 +656,14 @@ struct inode {
 	void			*i_private; /* fs or device private pointer */
 };
 
+static inline unsigned int inode_streamid(struct inode *inode)
+{
+	if (inode)
+		return inode->i_stream;
+
+	return 0;
+}
+
 static inline unsigned int i_blocksize(const struct inode *node)
 {
 	return (1 << node->i_blkbits);
-- 
2.7.4

[PATCH 04/11] fs: add support for allowing applications to pass in write life time hints

[Jens Axboe]

Add four flags for the pwritev2(2) system call, allowing an application
to give the kernel a hint about what on-media life times can be
expected from a given write.

The intent is for these values to be relative to each other, no
absolute meaning should be attached to these flag names.

Define IOCB flags to carry this information over, and finally
transform them into the block defined stream values.

Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/read_write.c         |  9 ++++++++-
 include/linux/fs.h      | 12 ++++++++++++
 include/uapi/linux/fs.h | 10 ++++++++++
 3 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/fs/read_write.c b/fs/read_write.c
index 47c1d4484df9..a9b0c3125e0f 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -678,7 +678,7 @@ static ssize_t do_iter_readv_writev(struct file *filp, struct iov_iter *iter,
 	struct kiocb kiocb;
 	ssize_t ret;
 
-	if (flags & ~(RWF_HIPRI | RWF_DSYNC | RWF_SYNC))
+	if (flags & ~(RWF_HIPRI | RWF_DSYNC | RWF_SYNC | RWF_WRITE_LIFE_MASK))
 		return -EOPNOTSUPP;
 
 	init_sync_kiocb(&kiocb, filp);
@@ -688,6 +688,13 @@ static ssize_t do_iter_readv_writev(struct file *filp, struct iov_iter *iter,
 		kiocb.ki_flags |= IOCB_DSYNC;
 	if (flags & RWF_SYNC)
 		kiocb.ki_flags |= (IOCB_DSYNC | IOCB_SYNC);
+	if (flags & RWF_WRITE_LIFE_MASK) {
+		struct inode *inode = file_inode(filp);
+
+		inode->i_stream = (flags & RWF_WRITE_LIFE_MASK) >>
+					RWF_WRITE_LIFE_SHIFT;
+		kiocb.ki_flags |= inode->i_stream << IOCB_WRITE_LIFE_SHIFT;
+	}
 	kiocb.ki_pos = *ppos;
 
 	if (type == READ)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 771e172d23d7..751a1046e87b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -269,6 +269,12 @@ struct writeback_control;
 #define IOCB_SYNC		(1 << 5)
 #define IOCB_WRITE		(1 << 6)
 
+/*
+ * Steal 4-bits for stream information, this allows 16 valid streams
+ */
+#define IOCB_WRITE_LIFE_SHIFT	7
+#define IOCB_WRITE_LIFE_MASK	(BIT(7) | BIT(8) | BIT(9) | BIT(10))
+
 struct kiocb {
 	struct file		*ki_filp;
 	loff_t			ki_pos;
@@ -292,6 +298,12 @@ static inline void init_sync_kiocb(struct kiocb *kiocb, struct file *filp)
 	};
 }
 
+static inline int iocb_streamid(const struct kiocb *iocb)
+{
+	return (iocb->ki_flags & IOCB_WRITE_LIFE_MASK) >>
+			IOCB_WRITE_LIFE_SHIFT;
+}
+
 /*
  * "descriptor" for what we're up to with a read.
  * This allows us to use the same read code yet
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index 24e61a54feaa..58b7ee06b380 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -361,4 +361,14 @@ struct fscrypt_key {
 #define RWF_DSYNC			0x00000002 /* per-IO O_DSYNC */
 #define RWF_SYNC			0x00000004 /* per-IO O_SYNC */
 
+/*
+ * Data life time write flags, steal 4 bits for that
+ */
+#define RWF_WRITE_LIFE_SHIFT		4
+#define RWF_WRITE_LIFE_MASK		0x000000f0 /* 4 bits of stream ID */
+#define RWF_WRITE_LIFE_SHORT		(1 << RWF_WRITE_LIFE_SHIFT)
+#define RWF_WRITE_LIFE_MEDIUM		(2 << RWF_WRITE_LIFE_SHIFT)
+#define RWF_WRITE_LIFE_LONG		(3 << RWF_WRITE_LIFE_SHIFT)
+#define RWF_WRITE_LIFE_EXTREME		(4 << RWF_WRITE_LIFE_SHIFT)
+
 #endif /* _UAPI_LINUX_FS_H */
-- 
2.7.4

[PATCH 05/11] block: add helpers for setting/checking stream validity

[Jens Axboe]

We map the RWF_WRITE_* life time flags to the internal flags.
Drivers can then, in turn, map those flags to a suitable stream
type.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 block/bio.c               | 16 ++++++++++++++++
 include/linux/bio.h       |  1 +
 include/linux/blk_types.h |  5 +++++
 3 files changed, 22 insertions(+)

diff --git a/block/bio.c b/block/bio.c
index 888e7801c638..25ea7c365aac 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -2082,6 +2082,22 @@ void bio_clone_blkcg_association(struct bio *dst, struct bio *src)
 
 #endif /* CONFIG_BLK_CGROUP */
 
+static const unsigned int rwf_write_to_opf_flag[] = {
+	0, REQ_WRITE_SHORT, REQ_WRITE_MEDIUM, REQ_WRITE_LONG, REQ_WRITE_EXTREME
+};
+
+/*
+ * 'stream_flags' is one of RWF_WRITE_LIFE_* values
+ */
+void bio_set_streamid(struct bio *bio, unsigned int rwf_flags)
+{
+	if (WARN_ON_ONCE(rwf_flags >= ARRAY_SIZE(rwf_write_to_opf_flag)))
+		return;
+
+	bio->bi_opf |= rwf_write_to_opf_flag[rwf_flags];
+}
+EXPORT_SYMBOL_GPL(bio_set_streamid);
+
 static void __init biovec_init_slabs(void)
 {
 	int i;
diff --git a/include/linux/bio.h b/include/linux/bio.h
index d1b04b0e99cf..a1b3145020ad 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -443,6 +443,7 @@ extern struct bio *bio_copy_kern(struct request_queue *, void *, unsigned int,
 				 gfp_t, int);
 extern void bio_set_pages_dirty(struct bio *bio);
 extern void bio_check_pages_dirty(struct bio *bio);
+extern void bio_set_streamid(struct bio *bio, unsigned int rwf_flags);
 
 void generic_start_io_acct(int rw, unsigned long sectors,
 			   struct hd_struct *part);
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 57d1eb530799..06c8c35f0288 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -323,4 +323,9 @@ struct blk_rq_stat {
 	u64 batch;
 };
 
+static inline bool blk_stream_valid(unsigned int opf)
+{
+	return (opf & REQ_WRITE_LIFE_MASK) != 0;
+}
+
 #endif /* __LINUX_BLK_TYPES_H */
-- 
2.7.4

[PATCH 06/11] fs: add O_DIRECT support for sending down bio stream information

[Jens Axboe]

Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/block_dev.c | 2 ++
 fs/direct-io.c | 2 ++
 fs/iomap.c     | 1 +
 3 files changed, 5 insertions(+)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 519599dddd36..31ba4a8f0a28 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -239,6 +239,7 @@ __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter,
 			should_dirty = true;
 	} else {
 		bio.bi_opf = dio_bio_write_op(iocb);
+		bio_set_streamid(&bio, iocb_streamid(iocb));
 		task_io_account_write(ret);
 	}
 
@@ -374,6 +375,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
 				bio_set_pages_dirty(bio);
 		} else {
 			bio->bi_opf = dio_bio_write_op(iocb);
+			bio_set_streamid(bio, iocb_streamid(iocb));
 			task_io_account_write(bio->bi_iter.bi_size);
 		}
 
diff --git a/fs/direct-io.c b/fs/direct-io.c
index a04ebea77de8..a770e82bb9f8 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -386,6 +386,8 @@ dio_bio_alloc(struct dio *dio, struct dio_submit *sdio,
 	else
 		bio->bi_end_io = dio_bio_end_io;
 
+	bio_set_streamid(bio, iocb_streamid(dio->iocb));
+
 	sdio->bio = bio;
 	sdio->logical_offset_in_bio = sdio->cur_page_fs_offset;
 }
diff --git a/fs/iomap.c b/fs/iomap.c
index 4b10892967a5..fa7d29632fbc 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -804,6 +804,7 @@ iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length,
 
 		if (dio->flags & IOMAP_DIO_WRITE) {
 			bio_set_op_attrs(bio, REQ_OP_WRITE, REQ_SYNC | REQ_IDLE);
+			bio_set_streamid(bio, inode_streamid(inode));
 			task_io_account_write(bio->bi_iter.bi_size);
 		} else {
 			bio_set_op_attrs(bio, REQ_OP_READ, 0);
-- 
2.7.4

[PATCH 07/11] fs: add support for buffered writeback to pass down stream information

[Jens Axboe]

Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/buffer.c | 14 +++++++++-----
 fs/mpage.c  |  1 +
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index 161be58c5cb0..8324c24751ca 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -49,7 +49,7 @@
 
 static int fsync_buffers_list(spinlock_t *lock, struct list_head *list);
 static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh,
-			 struct writeback_control *wbc);
+			 unsigned int stream, struct writeback_control *wbc);
 
 #define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers)
 
@@ -1829,7 +1829,8 @@ int __block_write_full_page(struct inode *inode, struct page *page,
 	do {
 		struct buffer_head *next = bh->b_this_page;
 		if (buffer_async_write(bh)) {
-			submit_bh_wbc(REQ_OP_WRITE, write_flags, bh, wbc);
+			submit_bh_wbc(REQ_OP_WRITE, write_flags, bh,
+					inode_streamid(inode), wbc);
 			nr_underway++;
 		}
 		bh = next;
@@ -1883,7 +1884,8 @@ int __block_write_full_page(struct inode *inode, struct page *page,
 		struct buffer_head *next = bh->b_this_page;
 		if (buffer_async_write(bh)) {
 			clear_buffer_dirty(bh);
-			submit_bh_wbc(REQ_OP_WRITE, write_flags, bh, wbc);
+			submit_bh_wbc(REQ_OP_WRITE, write_flags, bh,
+					inode_streamid(inode), wbc);
 			nr_underway++;
 		}
 		bh = next;
@@ -3091,7 +3093,7 @@ void guard_bio_eod(int op, struct bio *bio)
 }
 
 static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh,
-			 struct writeback_control *wbc)
+			 unsigned int stream, struct writeback_control *wbc)
 {
 	struct bio *bio;
 
@@ -3130,6 +3132,8 @@ static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh,
 	/* Take care of bh's that straddle the end of the device */
 	guard_bio_eod(op, bio);
 
+	bio_set_streamid(bio, stream);
+
 	if (buffer_meta(bh))
 		op_flags |= REQ_META;
 	if (buffer_prio(bh))
@@ -3142,7 +3146,7 @@ static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh,
 
 int submit_bh(int op, int op_flags, struct buffer_head *bh)
 {
-	return submit_bh_wbc(op, op_flags, bh, NULL);
+	return submit_bh_wbc(op, op_flags, bh, 0, NULL);
 }
 EXPORT_SYMBOL(submit_bh);
 
diff --git a/fs/mpage.c b/fs/mpage.c
index baff8f820c29..a9d40c0c053e 100644
--- a/fs/mpage.c
+++ b/fs/mpage.c
@@ -614,6 +614,7 @@ static int __mpage_writepage(struct page *page, struct writeback_control *wbc,
 			goto confused;
 
 		wbc_init_bio(wbc, bio);
+		bio_set_streamid(bio, inode_streamid(inode));
 	}
 
 	/*
-- 
2.7.4

[PATCH 08/11] ext4: add support for passing in stream information for buffered writes

[Jens Axboe]

Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/ext4/page-io.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 1a82138ba739..033b5bfa4e0b 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -350,6 +350,7 @@ void ext4_io_submit(struct ext4_io_submit *io)
 		int io_op_flags = io->io_wbc->sync_mode == WB_SYNC_ALL ?
 				  REQ_SYNC : 0;
 		bio_set_op_attrs(io->io_bio, REQ_OP_WRITE, io_op_flags);
+		bio_set_streamid(io->io_bio, inode_streamid(io->io_end->inode));
 		submit_bio(io->io_bio);
 	}
 	io->io_bio = NULL;
@@ -396,6 +397,7 @@ static int io_submit_add_bh(struct ext4_io_submit *io,
 		ret = io_submit_init_bio(io, bh);
 		if (ret)
 			return ret;
+		bio_set_streamid(io->io_bio, inode_streamid(inode));
 	}
 	ret = bio_add_page(io->io_bio, page, bh->b_size, bh_offset(bh));
 	if (ret != bh->b_size)
-- 
2.7.4

[PATCH 09/11] xfs: add support for passing in stream information for buffered writes

[Jens Axboe]

Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/xfs/xfs_aops.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 09af0f7cd55e..9770be0140ad 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -505,6 +505,7 @@ xfs_submit_ioend(
 		return status;
 	}
 
+	bio_set_streamid(ioend->io_bio, inode_streamid(ioend->io_inode));
 	submit_bio(ioend->io_bio);
 	return 0;
 }
@@ -564,6 +565,7 @@ xfs_chain_bio(
 	bio_chain(ioend->io_bio, new);
 	bio_get(ioend->io_bio);		/* for xfs_destroy_ioend */
 	ioend->io_bio->bi_opf = REQ_OP_WRITE | wbc_to_write_flags(wbc);
+	bio_set_streamid(ioend->io_bio, inode_streamid(ioend->io_inode));
 	submit_bio(ioend->io_bio);
 	ioend->io_bio = new;
 }
-- 
2.7.4

[PATCH 10/11] btrfs: add support for passing in stream information for buffered writes

[Jens Axboe]

Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/btrfs/extent_io.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index d3619e010005..b245085e8f10 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2827,6 +2827,7 @@ static int submit_extent_page(int op, int op_flags, struct extent_io_tree *tree,
 	bio->bi_end_io = end_io_func;
 	bio->bi_private = tree;
 	bio_set_op_attrs(bio, op, op_flags);
+	bio_set_streamid(bio, inode_streamid(page->mapping->host));
 	if (wbc) {
 		wbc_init_bio(wbc, bio);
 		wbc_account_io(wbc, page, page_size);
-- 
2.7.4

[PATCH 11/11] nvme: add support for streams and directives

[Jens Axboe]

This adds support for Directives in NVMe, particular for the Streams
directive. Support for Directives is a new feature in NVMe 1.3. It
allows a user to pass in information about where to store the data,
so that it the device can do so most effiently. If an application is
managing and writing data with different life times, mixing differently
retentioned data onto the same locations on flash can cause write
amplification to grow. This, in turn, will reduce performance and
life time of the device.

We default to allocating 4 streams per name space, but it is
configurable with the 'streams_per_ns' module option. If a write stream
is set in a write, flag is as such before sending it to the device.

Some debug stuff in this patch, dumping streams ID params when
we load nvme.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 drivers/nvme/host/core.c | 146 +++++++++++++++++++++++++++++++++++++++++++++++
 drivers/nvme/host/nvme.h |   1 +
 include/linux/nvme.h     |  48 ++++++++++++++++
 3 files changed, 195 insertions(+)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 903d5813023a..a389d62a528b 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -65,6 +65,10 @@ static bool force_apst;
 module_param(force_apst, bool, 0644);
 MODULE_PARM_DESC(force_apst, "allow APST for newly enumerated devices even if quirked off");
 
+static char streams_per_ns = 4;
+module_param(streams_per_ns, byte, 0644);
+MODULE_PARM_DESC(streams_per_ns, "if available, allocate this many streams per NS");
+
 static LIST_HEAD(nvme_ctrl_list);
 static DEFINE_SPINLOCK(dev_list_lock);
 
@@ -331,9 +335,34 @@ static inline int nvme_setup_discard(struct nvme_ns *ns, struct request *req,
 	return BLK_MQ_RQ_QUEUE_OK;
 }
 
+static unsigned int nvme_get_write_stream(struct nvme_ns *ns,
+					  struct request *req)
+{
+	unsigned int streamid = 0;
+
+	if (req_op(req) != REQ_OP_WRITE || !blk_stream_valid(req->cmd_flags) ||
+	    !ns->nr_streams)
+		return 0;
+
+	if (req->cmd_flags & REQ_WRITE_SHORT)
+		streamid = 1;
+	else if (req->cmd_flags & REQ_WRITE_MEDIUM)
+		streamid = 2;
+	else if (req->cmd_flags & REQ_WRITE_LONG)
+		streamid = 3;
+	else if (req->cmd_flags & REQ_WRITE_EXTREME)
+		streamid = 4;
+
+	if (streamid < BLK_MAX_STREAM)
+		req->q->stream_writes[streamid] += blk_rq_bytes(req) >> 9;
+
+	return (streamid % (ns->nr_streams + 1));
+}
+
 static inline void nvme_setup_rw(struct nvme_ns *ns, struct request *req,
 		struct nvme_command *cmnd)
 {
+	unsigned int stream;
 	u16 control = 0;
 	u32 dsmgmt = 0;
 
@@ -351,6 +380,12 @@ static inline void nvme_setup_rw(struct nvme_ns *ns, struct request *req,
 	cmnd->rw.slba = cpu_to_le64(nvme_block_nr(ns, blk_rq_pos(req)));
 	cmnd->rw.length = cpu_to_le16((blk_rq_bytes(req) >> ns->lba_shift) - 1);
 
+	stream = nvme_get_write_stream(ns, req);
+	if (stream) {
+		control |= NVME_RW_DTYPE_STREAMS;
+		dsmgmt |= (stream << 16);
+	}
+
 	if (ns->ms) {
 		switch (ns->pi_type) {
 		case NVME_NS_DPS_PI_TYPE3:
@@ -1073,6 +1108,109 @@ static int nvme_revalidate_disk(struct gendisk *disk)
 	return 0;
 }
 
+static int nvme_enable_streams(struct nvme_ns *ns)
+{
+	struct nvme_command c;
+
+	memset(&c, 0, sizeof(c));
+
+	c.directive.opcode = nvme_admin_directive_send;
+	c.directive.nsid = cpu_to_le32(ns->ns_id);
+	c.directive.doper = NVME_DIR_SND_ID_OP_ENABLE;
+	c.directive.dtype = NVME_DIR_IDENTIFY;
+	c.directive.tdtype = NVME_DIR_STREAMS;
+	c.directive.endir = NVME_DIR_ENDIR;
+
+	return nvme_submit_sync_cmd(ns->ctrl->admin_q, &c, NULL, 0);
+}
+
+static int nvme_streams_params(struct nvme_ns *ns)
+{
+	struct nvme_ctrl *ctrl = ns->ctrl;
+	struct streams_directive_params s;
+	struct nvme_command c;
+	int ret;
+
+	memset(&c, 0, sizeof(c));
+	memset(&s, 0, sizeof(s));
+
+	c.directive.opcode = nvme_admin_directive_recv;
+	c.directive.nsid = cpu_to_le32(ns->ns_id);
+	c.directive.numd = sizeof(s);
+	c.directive.doper = NVME_DIR_RCV_ST_OP_PARAM;
+	c.directive.dtype = NVME_DIR_STREAMS;
+
+	ret = nvme_submit_sync_cmd(ctrl->admin_q, &c, &s, sizeof(s));
+	if (ret)
+		return ret;
+
+	s.msl = le16_to_cpu(s.msl);
+	s.nssa = le16_to_cpu(s.nssa);
+	s.nsso = le16_to_cpu(s.nsso);
+	s.sws = le32_to_cpu(s.sws);
+	s.sgs = le16_to_cpu(s.sgs);
+	s.nsa = le16_to_cpu(s.nsa);
+	s.nso = le16_to_cpu(s.nso);
+
+	dev_info(ctrl->device, "streams: msl=%u, nssa=%u, nsso=%u, sws=%u "
+				"sgs=%u, nsa=%u, nso=%u\n", s.msl, s.nssa,
+				s.nsso, s.sws, s.sgs, s.nsa, s.nso);
+	return 0;
+}
+
+static int nvme_streams_allocate(struct nvme_ns *ns, unsigned int streams)
+{
+	struct nvme_command c;
+
+	memset(&c, 0, sizeof(c));
+
+	c.directive.opcode = nvme_admin_directive_recv;
+	c.directive.nsid = cpu_to_le32(ns->ns_id);
+	c.directive.doper = NVME_DIR_RCV_ST_OP_RESOURCE;
+	c.directive.dtype = NVME_DIR_STREAMS;
+	c.directive.endir = streams;
+
+	return nvme_submit_sync_cmd(ns->ctrl->admin_q, &c, NULL, 0);
+}
+
+static int nvme_streams_deallocate(struct nvme_ns *ns)
+{
+	struct nvme_command c;
+
+	memset(&c, 0, sizeof(c));
+
+	c.directive.opcode = nvme_admin_directive_send;
+	c.directive.nsid = cpu_to_le32(ns->ns_id);
+	c.directive.doper = NVME_DIR_SND_ST_OP_REL_RSC;
+	c.directive.dtype = NVME_DIR_STREAMS;
+
+	return nvme_submit_sync_cmd(ns->ctrl->admin_q, &c, NULL, 0);
+}
+
+static void nvme_config_streams(struct nvme_ns *ns)
+{
+	int ret;
+
+	ret = nvme_enable_streams(ns);
+	if (ret)
+		return;
+
+	ret = nvme_streams_params(ns);
+	if (ret)
+		return;
+
+	ret = nvme_streams_allocate(ns, streams_per_ns);
+	if (ret)
+		return;
+
+	ret = nvme_streams_params(ns);
+	if (ret)
+		return;
+
+	ns->nr_streams = streams_per_ns;
+	dev_info(ns->ctrl->device, "successfully enabled streams\n");
+}
+
 static char nvme_pr_type(enum pr_type type)
 {
 	switch (type) {
@@ -1606,6 +1744,9 @@ int nvme_init_identify(struct nvme_ctrl *ctrl)
 	ctrl->sgls = le32_to_cpu(id->sgls);
 	ctrl->kas = le16_to_cpu(id->kas);
 
+	if (ctrl->oacs & NVME_CTRL_OACS_DIRECTIVES)
+		dev_info(ctrl->dev, "supports directives\n");
+
 	ctrl->npss = id->npss;
 	prev_apsta = ctrl->apsta;
 	if (ctrl->quirks & NVME_QUIRK_NO_APST) {
@@ -2060,6 +2201,9 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid)
 		goto out_free_id;
 	}
 
+	if (ctrl->oacs & NVME_CTRL_OACS_DIRECTIVES)
+		nvme_config_streams(ns);
+
 	disk = alloc_disk_node(0, node);
 	if (!disk)
 		goto out_free_id;
@@ -2112,6 +2256,8 @@ static void nvme_ns_remove(struct nvme_ns *ns)
 					&nvme_ns_attr_group);
 		if (ns->ndev)
 			nvme_nvm_unregister_sysfs(ns);
+		if (ns->nr_streams)
+			nvme_streams_deallocate(ns);
 		del_gendisk(ns->disk);
 		blk_cleanup_queue(ns->queue);
 	}
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 9d6a070d4391..dc87c8284259 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -192,6 +192,7 @@ struct nvme_ns {
 	u8 uuid[16];
 
 	unsigned ns_id;
+	unsigned nr_streams;
 	int lba_shift;
 	u16 ms;
 	bool ext;
diff --git a/include/linux/nvme.h b/include/linux/nvme.h
index b625bacf37ef..8b2f5b140134 100644
--- a/include/linux/nvme.h
+++ b/include/linux/nvme.h
@@ -245,6 +245,7 @@ enum {
 	NVME_CTRL_ONCS_WRITE_ZEROES		= 1 << 3,
 	NVME_CTRL_VWC_PRESENT			= 1 << 0,
 	NVME_CTRL_OACS_SEC_SUPP                 = 1 << 0,
+	NVME_CTRL_OACS_DIRECTIVES		= 1 << 5,
 	NVME_CTRL_OACS_DBBUF_SUPP		= 1 << 7,
 };
 
@@ -295,6 +296,19 @@ enum {
 };
 
 enum {
+	NVME_DIR_IDENTIFY		= 0x00,
+	NVME_DIR_STREAMS		= 0x01,
+	NVME_DIR_SND_ID_OP_ENABLE	= 0x01,
+	NVME_DIR_SND_ST_OP_REL_ID	= 0x01,
+	NVME_DIR_SND_ST_OP_REL_RSC	= 0x02,
+	NVME_DIR_RCV_ID_OP_PARAM	= 0x01,
+	NVME_DIR_RCV_ST_OP_PARAM	= 0x01,
+	NVME_DIR_RCV_ST_OP_STATUS	= 0x02,
+	NVME_DIR_RCV_ST_OP_RESOURCE	= 0x03,
+	NVME_DIR_ENDIR			= 0x01,
+};
+
+enum {
 	NVME_NS_FEAT_THIN	= 1 << 0,
 	NVME_NS_FLBAS_LBA_MASK	= 0xf,
 	NVME_NS_FLBAS_META_EXT	= 0x10,
@@ -535,6 +549,7 @@ enum {
 	NVME_RW_PRINFO_PRCHK_APP	= 1 << 11,
 	NVME_RW_PRINFO_PRCHK_GUARD	= 1 << 12,
 	NVME_RW_PRINFO_PRACT		= 1 << 13,
+	NVME_RW_DTYPE_STREAMS		= 1 << 4,
 };
 
 struct nvme_dsm_cmd {
@@ -604,6 +619,8 @@ enum nvme_admin_opcode {
 	nvme_admin_download_fw		= 0x11,
 	nvme_admin_ns_attach		= 0x15,
 	nvme_admin_keep_alive		= 0x18,
+	nvme_admin_directive_send	= 0x19,
+	nvme_admin_directive_recv	= 0x1a,
 	nvme_admin_dbbuf		= 0x7C,
 	nvme_admin_format_nvm		= 0x80,
 	nvme_admin_security_send	= 0x81,
@@ -756,6 +773,24 @@ struct nvme_get_log_page_command {
 	__u32			rsvd14[2];
 };
 
+struct nvme_directive_cmd {
+	__u8			opcode;
+	__u8			flags;
+	__u16			command_id;
+	__le32			nsid;
+	__u64			rsvd2[2];
+	union nvme_data_ptr	dptr;
+	__le32			numd;
+	__u8			doper;
+	__u8			dtype;
+	__le16			dspec;
+	__u8			endir;
+	__u8			tdtype;
+	__u16			rsvd15;
+
+	__u32			rsvd16[3];
+};
+
 /*
  * Fabrics subcommands.
  */
@@ -886,6 +921,18 @@ struct nvme_dbbuf {
 	__u32			rsvd12[6];
 };
 
+struct streams_directive_params {
+	__u16	msl;
+	__u16	nssa;
+	__u16	nsso;
+	__u8	rsvd[10];
+	__u32	sws;
+	__u16	sgs;
+	__u16	nsa;
+	__u16	nso;
+	__u8	rsvd2[6];
+};
+
 struct nvme_command {
 	union {
 		struct nvme_common_command common;
@@ -906,6 +953,7 @@ struct nvme_command {
 		struct nvmf_property_set_command prop_set;
 		struct nvmf_property_get_command prop_get;
 		struct nvme_dbbuf dbbuf;
+		struct nvme_directive_cmd directive;
 	};
 };
 
-- 
2.7.4

Re: [PATCH 03/11] fs: add support for an inode to carry stream related data

[Christoph Hellwig]

On Wed, Jun 14, 2017 at 01:05:26PM -0600, Jens Axboe wrote:
> No functional changes in this patch, just in preparation for
> allowing applications to pass in hints about data life times
> for writes.
> 
> Pack the i_stream field into a 2-byte hole, so we don't grow
> the size of the inode.

Can't we find space for 4 flags somewhere else?

Re: [PATCH 04/11] fs: add support for allowing applications to pass in write life time hints

[Christoph Hellwig]

On Wed, Jun 14, 2017 at 01:05:27PM -0600, Jens Axboe wrote:
> Add four flags for the pwritev2(2) system call, allowing an application
> to give the kernel a hint about what on-media life times can be
> expected from a given write.
> 
> The intent is for these values to be relative to each other, no
> absolute meaning should be attached to these flag names.
> 
> Define IOCB flags to carry this information over, and finally
> transform them into the block defined stream values.

Note that we also have the RWF_NOWAIT flag pending, with which this
would clash.  Maybe move it to the end of the space.

Re: [PATCH 05/11] block: add helpers for setting/checking stream validity

[Christoph Hellwig]

> +static const unsigned int rwf_write_to_opf_flag[] = {
> +	0, REQ_WRITE_SHORT, REQ_WRITE_MEDIUM, REQ_WRITE_LONG, REQ_WRITE_EXTREME
> +};



> +
> +/*
> + * 'stream_flags' is one of RWF_WRITE_LIFE_* values
> + */
> +void bio_set_streamid(struct bio *bio, unsigned int rwf_flags)
> +{
> +	if (WARN_ON_ONCE(rwf_flags >= ARRAY_SIZE(rwf_write_to_opf_flag)))
> +		return;
> +
> +	bio->bi_opf |= rwf_write_to_opf_flag[rwf_flags];
> +}
> +EXPORT_SYMBOL_GPL(bio_set_streamid);

I'd move the bio->bi_opf assignment outş for a call like:

	bio->bi_opf |= bio_op_write_bucket(flags);

and preferably move the flags masking / shifting into the helper as
well.

>  };
>  
> +static inline bool blk_stream_valid(unsigned int opf)
> +{
> +	return (opf & REQ_WRITE_LIFE_MASK) != 0;
> +}

Replace the stream name here with lifetime or similar as well?

Re: [PATCH 11/11] nvme: add support for streams and directives

[Christoph Hellwig]

> +static unsigned int nvme_get_write_stream(struct nvme_ns *ns,
> +					  struct request *req)
> +{
> +	unsigned int streamid = 0;
> +
> +	if (req_op(req) != REQ_OP_WRITE || !blk_stream_valid(req->cmd_flags) ||
> +	    !ns->nr_streams)
> +		return 0;

Might make more sense to do this check in the caller?

> +
> +	if (req->cmd_flags & REQ_WRITE_SHORT)
> +		streamid = 1;
> +	else if (req->cmd_flags & REQ_WRITE_MEDIUM)
> +		streamid = 2;
> +	else if (req->cmd_flags & REQ_WRITE_LONG)
> +		streamid = 3;
> +	else if (req->cmd_flags & REQ_WRITE_EXTREME)
> +		streamid = 4;
> +
> +	if (streamid < BLK_MAX_STREAM)

Can happen per the index above.

> +		req->q->stream_writes[streamid] += blk_rq_bytes(req) >> 9;
> +
> +	return (streamid % (ns->nr_streams + 1));

Should we do smarted collapsing?  e.g. short + medium and long + extreme
for two?  What for three?  Does one extra stream make sense in this
scheme?

> +	dev_info(ctrl->device, "streams: msl=%u, nssa=%u, nsso=%u, sws=%u "
> +				"sgs=%u, nsa=%u, nso=%u\n", s.msl, s.nssa,
> +				s.nsso, s.sws, s.sgs, s.nsa, s.nso);

Way to chatty.

> +	if (ctrl->oacs & NVME_CTRL_OACS_DIRECTIVES)
> +		dev_info(ctrl->dev, "supports directives\n");

Same.  Use nvme-cli for that sort of info.

>  	ctrl->npss = id->npss;
>  	prev_apsta = ctrl->apsta;
>  	if (ctrl->quirks & NVME_QUIRK_NO_APST) {
> @@ -2060,6 +2201,9 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid)
>  		goto out_free_id;
>  	}
>  
> +	if (ctrl->oacs & NVME_CTRL_OACS_DIRECTIVES)
> +		nvme_config_streams(ns);

This sets aside four streams on any device that supports them, and
will probably kill performance on them unless you have a workload
that actually uses those streams.  I think they need to be allocated
lazily.

Re: [PATCH 03/11] fs: add support for an inode to carry stream related data

[Jens Axboe]

On 06/14/2017 02:25 PM, Christoph Hellwig wrote:
> On Wed, Jun 14, 2017 at 01:05:26PM -0600, Jens Axboe wrote:
>> No functional changes in this patch, just in preparation for
>> allowing applications to pass in hints about data life times
>> for writes.
>>
>> Pack the i_stream field into a 2-byte hole, so we don't grow
>> the size of the inode.
> 
> Can't we find space for 4 flags somewhere else?

Where? I can stuff them in i_flags? But apart from that, stealing
space in a hole seems the sanest.

-- 
Jens Axboe

Re: [PATCH 04/11] fs: add support for allowing applications to pass in write life time hints

[Jens Axboe]

On 06/14/2017 02:26 PM, Christoph Hellwig wrote:
> On Wed, Jun 14, 2017 at 01:05:27PM -0600, Jens Axboe wrote:
>> Add four flags for the pwritev2(2) system call, allowing an application
>> to give the kernel a hint about what on-media life times can be
>> expected from a given write.
>>
>> The intent is for these values to be relative to each other, no
>> absolute meaning should be attached to these flag names.
>>
>> Define IOCB flags to carry this information over, and finally
>> transform them into the block defined stream values.
> 
> Note that we also have the RWF_NOWAIT flag pending, with which this
> would clash.  Maybe move it to the end of the space.

That's a trivial thing to resolve. Whomever goes last can resolve
that. I can put them at the end if you feel strongly about it, I
personally don't really care.

-- 
Jens Axboe

Re: [PATCH 01/11] block: add support for carrying stream information in a bio

[Christoph Hellwig]

Btw, I think these could also easily map to DSM field in the NVMe
write command, except that these unfortunately mix in read information
as well.

> +	__REQ_WRITE_SHORT,	/* short life time write */

-> Frequent writes and infrequent reads to the LBA range indicated.

or

-> Frequent writes and frequent reads to the LBA range indicated.

> +	__REQ_WRITE_MEDIUM,	/* medium life time write */

-> Typical number of reads and writes expected for this LBA range.

> +	__REQ_WRITE_LONG,	/* long life time write */

-> Infrequent writes and infrequent reads to the LBA range indicated.

or

-> Infrequent writes and frequent reads to the LBA range indicated.

> +	__REQ_WRITE_EXTREME,	/* extremely long life time write */

-> One time write. E.g. command is due to virus scan, backup, file
copy, or archive.

Re: [PATCH 05/11] block: add helpers for setting/checking stream validity

[Jens Axboe]

On 06/14/2017 02:28 PM, Christoph Hellwig wrote:
>> +static const unsigned int rwf_write_to_opf_flag[] = {
>> +	0, REQ_WRITE_SHORT, REQ_WRITE_MEDIUM, REQ_WRITE_LONG, REQ_WRITE_EXTREME
>> +};
> 
> 
> 
>> +
>> +/*
>> + * 'stream_flags' is one of RWF_WRITE_LIFE_* values
>> + */
>> +void bio_set_streamid(struct bio *bio, unsigned int rwf_flags)
>> +{
>> +	if (WARN_ON_ONCE(rwf_flags >= ARRAY_SIZE(rwf_write_to_opf_flag)))
>> +		return;
>> +
>> +	bio->bi_opf |= rwf_write_to_opf_flag[rwf_flags];
>> +}
>> +EXPORT_SYMBOL_GPL(bio_set_streamid);
> 
> I'd move the bio->bi_opf assignment outş for a call like:
> 
> 	bio->bi_opf |= bio_op_write_bucket(flags);
> 
> and preferably move the flags masking / shifting into the helper as
> well.

OK, I can do that.

>> +static inline bool blk_stream_valid(unsigned int opf)
>> +{
>> +	return (opf & REQ_WRITE_LIFE_MASK) != 0;
>> +}
> 
> Replace the stream name here with lifetime or similar as well?

Yeah, I thought about that after sending v3 out. I should do that
everywhere.

-- 
Jens Axboe

Re: [PATCH 11/11] nvme: add support for streams and directives

[Jens Axboe]

On 06/14/2017 02:32 PM, Christoph Hellwig wrote:
>> +static unsigned int nvme_get_write_stream(struct nvme_ns *ns,
>> +					  struct request *req)
>> +{
>> +	unsigned int streamid = 0;
>> +
>> +	if (req_op(req) != REQ_OP_WRITE || !blk_stream_valid(req->cmd_flags) ||
>> +	    !ns->nr_streams)
>> +		return 0;
> 
> Might make more sense to do this check in the caller?

OK, will fix up.

>> +	if (req->cmd_flags & REQ_WRITE_SHORT)
>> +		streamid = 1;
>> +	else if (req->cmd_flags & REQ_WRITE_MEDIUM)
>> +		streamid = 2;
>> +	else if (req->cmd_flags & REQ_WRITE_LONG)
>> +		streamid = 3;
>> +	else if (req->cmd_flags & REQ_WRITE_EXTREME)
>> +		streamid = 4;
>> +
>> +	if (streamid < BLK_MAX_STREAM)
> 
> Can happen per the index above.

True, that's a leftover from the previous version.

>> +		req->q->stream_writes[streamid] += blk_rq_bytes(req) >> 9;
>> +
>> +	return (streamid % (ns->nr_streams + 1));
> 
> Should we do smarted collapsing?  e.g. short + medium and long + extreme
> for two?  What for three?  Does one extra stream make sense in this
> scheme?

Collapsing is probably saner than round-robin. I'd tend to collapse on
the longer life time end of things, logically that would make the most
sense.

>> +	dev_info(ctrl->device, "streams: msl=%u, nssa=%u, nsso=%u, sws=%u "
>> +				"sgs=%u, nsa=%u, nso=%u\n", s.msl, s.nssa,
>> +				s.nsso, s.sws, s.sgs, s.nsa, s.nso);
> 
> Way to chatty.

Sure, that's mentioned in the changelog, that stuff will go.

>> +	if (ctrl->oacs & NVME_CTRL_OACS_DIRECTIVES)
>> +		dev_info(ctrl->dev, "supports directives\n");
> 
> Same.  Use nvme-cli for that sort of info.

Ditto

>>  	ctrl->npss = id->npss;
>>  	prev_apsta = ctrl->apsta;
>>  	if (ctrl->quirks & NVME_QUIRK_NO_APST) {
>> @@ -2060,6 +2201,9 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid)
>>  		goto out_free_id;
>>  	}
>>  
>> +	if (ctrl->oacs & NVME_CTRL_OACS_DIRECTIVES)
>> +		nvme_config_streams(ns);
> 
> This sets aside four streams on any device that supports them, and
> will probably kill performance on them unless you have a workload
> that actually uses those streams.  I think they need to be allocated
> lazily.

That's a good point, I have been thinking about how best to handle this.
I don't want an API for this, but doing it lazy would be fine. When we
see a write with a life time attached, kick off background setup of
streams. Until that's done, don't use any streams. Once setup, we'll
mark it as we currently do now.

How's that?

-- 
Jens Axboe

Re: [PATCH 01/11] block: add support for carrying stream information in a bio

[Jens Axboe]

On 06/14/2017 02:37 PM, Christoph Hellwig wrote:
> Btw, I think these could also easily map to DSM field in the NVMe
> write command, except that these unfortunately mix in read information
> as well.

But that's the problem, they are read/write mixed flags. I'd much
rather keep them separate. If some application finds it useful
to specify read access patterns, we should have separate flags for
those imho.

-- 
Jens Axboe

Re: [PATCH 10/11] btrfs: add support for passing in stream information for buffered writes

[Chris Mason]

On Wed, Jun 14, 2017 at 01:05:33PM -0600, Jens Axboe wrote:
>Reviewed-by: Andreas Dilger <adilger@dilger.ca>
>Signed-off-by: Jens Axboe <axboe@kernel.dk>

Thanks Jens!

Signed-off-by: Chris Mason <clm@fb.com>

>---
> fs/btrfs/extent_io.c | 1 +
> 1 file changed, 1 insertion(+)
>
>diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
>index d3619e010005..b245085e8f10 100644
>--- a/fs/btrfs/extent_io.c
>+++ b/fs/btrfs/extent_io.c
>@@ -2827,6 +2827,7 @@ static int submit_extent_page(int op, int op_flags, struct extent_io_tree *tree,
> 	bio->bi_end_io = end_io_func;
> 	bio->bi_private = tree;
> 	bio_set_op_attrs(bio, op, op_flags);
>+	bio_set_streamid(bio, inode_streamid(page->mapping->host));
> 	if (wbc) {
> 		wbc_init_bio(wbc, bio);
> 		wbc_account_io(wbc, page, page_size);
>-- 
>2.7.4
>

Re: [PATCH 03/11] fs: add support for an inode to carry stream related data

[Jens Axboe]

On 06/15/2017 02:17 AM, Christoph Hellwig wrote:
> On Wed, Jun 14, 2017 at 09:45:04PM -0600, Jens Axboe wrote:
>> No functional changes in this patch, just in preparation for
>> allowing applications to pass in hints about data life times
>> for writes.
>>
>> Pack the i_write_hint field into a 2-byte hole, so we don't grow
>> the size of the inode.
> 
> A u8 should be plenty.  But talking about the representation -
> your write lifetime hints are a 5 option enum basically.  I wonder
> if we really should encode it as flags, or if we should have an
> enum (which could be packed into a 3-bit bitfield) and then pass
> it down the stack in that form instead of changing the representation
> N times.

If we keep the RWF_WRITE_LIFE_* flags, then yes, I think we should
unify the RWF_WRITE_LIFE_*, IOCB_WRITE_LIFE_*, and REQ_WRITE_LIFE_*
flags into a specific type.


-- 
Jens Axboe

Re: [PATCH 03/11] fs: add support for an inode to carry stream related data

[Christoph Hellwig]

On Wed, Jun 14, 2017 at 09:45:04PM -0600, Jens Axboe wrote:
> No functional changes in this patch, just in preparation for
> allowing applications to pass in hints about data life times
> for writes.
> 
> Pack the i_write_hint field into a 2-byte hole, so we don't grow
> the size of the inode.

A u8 should be plenty.  But talking about the representation -
your write lifetime hints are a 5 option enum basically.  I wonder
if we really should encode it as flags, or if we should have an
enum (which could be packed into a 3-bit bitfield) and then pass
it down the stack in that form instead of changing the representation
N times.

[PATCH 03/11] fs: add support for an inode to carry stream related data

[Jens Axboe]

No functional changes in this patch, just in preparation for
allowing applications to pass in hints about data life times
for writes.

Pack the i_write_hint field into a 2-byte hole, so we don't grow
the size of the inode.

Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/inode.c         | 1 +
 include/linux/fs.h | 9 +++++++++
 2 files changed, 10 insertions(+)

diff --git a/fs/inode.c b/fs/inode.c
index db5914783a71..bd8bf44f3f31 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -149,6 +149,7 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
 	inode->i_blocks = 0;
 	inode->i_bytes = 0;
 	inode->i_generation = 0;
+	inode->i_write_hint = 0;
 	inode->i_pipe = NULL;
 	inode->i_bdev = NULL;
 	inode->i_cdev = NULL;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 803e5a9b2654..f4f9df8ed059 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -591,6 +591,7 @@ struct inode {
 	struct timespec		i_ctime;
 	spinlock_t		i_lock;	/* i_blocks, i_bytes, maybe i_size */
 	unsigned short          i_bytes;
+	unsigned short		i_write_hint;
 	unsigned int		i_blkbits;
 	blkcnt_t		i_blocks;
 
@@ -655,6 +656,14 @@ struct inode {
 	void			*i_private; /* fs or device private pointer */
 };
 
+static inline unsigned int inode_write_hint(struct inode *inode)
+{
+	if (inode)
+		return inode->i_write_hint;
+
+	return 0;
+}
+
 static inline unsigned int i_blocksize(const struct inode *node)
 {
 	return (1 << node->i_blkbits);
-- 
2.7.4