[dm-devel] [PATCH V3 0/3] block/dm: support bio polling

[dm-devel] [PATCH V3 0/3] block/dm: support bio polling

[Ming Lei]

Hello Guys,

Based on Christoph's bio based polling model[1], implement DM bio polling
with one very simple approach.

Patch 1 adds helper of blk_queue_poll().

Patch 2 adds .bio_poll() callback to block_device_operations, so bio
driver can implement its own logic for io polling.

Patch 3 implements bio polling for device mapper.


V3:
	- patch style change as suggested by Christoph(2/3)
	- fix kernel panic issue caused by nested dm polling, which is found
	  & figured out by Jeffle Xu (3/3)
	- re-organize setup polling code (3/3)
	- remove RFC

V2:
	- drop patch to add new fields into bio
	- support io polling for dm native bio splitting
	- add comment

Ming Lei (3):
  block: add helper of blk_queue_poll
  block: add ->poll_bio to block_device_operations
  dm: support bio polling

 block/blk-core.c         |  18 +++---
 block/blk-sysfs.c        |   4 +-
 block/genhd.c            |   2 +
 drivers/md/dm-table.c    |  24 +++++++
 drivers/md/dm.c          | 131 ++++++++++++++++++++++++++++++++++++++-
 drivers/nvme/host/core.c |   2 +-
 include/linux/blkdev.h   |   2 +
 7 files changed, 170 insertions(+), 13 deletions(-)

-- 
2.31.1

--
dm-devel mailing list
dm-devel@redhat.com
https://listman.redhat.com/mailman/listinfo/dm-devel

[dm-devel] [PATCH V3 1/3] block: add helper of blk_queue_poll

[Ming Lei]

There has been 3 users, and will be more, so add one such helper.

Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Jeffle Xu <jefflexu@linux.alibaba.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 block/blk-core.c         | 5 ++---
 block/blk-sysfs.c        | 4 ++--
 drivers/nvme/host/core.c | 2 +-
 include/linux/blkdev.h   | 1 +
 4 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 531176578221..1e24c71c6738 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -835,7 +835,7 @@ static noinline_for_stack bool submit_bio_checks(struct bio *bio)
 		}
 	}
 
-	if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
+	if (!blk_queue_poll(q))
 		bio->bi_opf &= ~REQ_POLLED;
 
 	switch (bio_op(bio)) {
@@ -1117,8 +1117,7 @@ int bio_poll(struct bio *bio, unsigned int flags)
 	blk_qc_t cookie = READ_ONCE(bio->bi_cookie);
 	int ret;
 
-	if (cookie == BLK_QC_T_NONE ||
-	    !test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
+	if (cookie == BLK_QC_T_NONE || !blk_queue_poll(q))
 		return 0;
 
 	if (current->plug)
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index f78e73ca6091..93dcf2dfaafd 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -422,13 +422,13 @@ static ssize_t queue_poll_delay_store(struct request_queue *q, const char *page,
 
 static ssize_t queue_poll_show(struct request_queue *q, char *page)
 {
-	return queue_var_show(test_bit(QUEUE_FLAG_POLL, &q->queue_flags), page);
+	return queue_var_show(blk_queue_poll(q), page);
 }
 
 static ssize_t queue_poll_store(struct request_queue *q, const char *page,
 				size_t count)
 {
-	if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
+	if (!blk_queue_poll(q))
 		return -EINVAL;
 	pr_info_ratelimited("writes to the poll attribute are ignored.\n");
 	pr_info_ratelimited("please use driver specific parameters instead.\n");
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index fe0b8da3de7f..e31c7704ef4d 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1025,7 +1025,7 @@ static void nvme_execute_rq_polled(struct request_queue *q,
 {
 	DECLARE_COMPLETION_ONSTACK(wait);
 
-	WARN_ON_ONCE(!test_bit(QUEUE_FLAG_POLL, &q->queue_flags));
+	WARN_ON_ONCE(!blk_queue_poll(q));
 
 	rq->cmd_flags |= REQ_POLLED;
 	rq->end_io_data = &wait;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 561b04117bd4..fc0ba0b80776 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -677,6 +677,7 @@ bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q);
 #define blk_queue_fua(q)	test_bit(QUEUE_FLAG_FUA, &(q)->queue_flags)
 #define blk_queue_registered(q)	test_bit(QUEUE_FLAG_REGISTERED, &(q)->queue_flags)
 #define blk_queue_nowait(q)	test_bit(QUEUE_FLAG_NOWAIT, &(q)->queue_flags)
+#define blk_queue_poll(q)	test_bit(QUEUE_FLAG_POLL, &(q)->queue_flags)
 
 extern void blk_set_pm_only(struct request_queue *q);
 extern void blk_clear_pm_only(struct request_queue *q);
-- 
2.31.1

--
dm-devel mailing list
dm-devel@redhat.com
https://listman.redhat.com/mailman/listinfo/dm-devel

[dm-devel] [PATCH V3 2/3] block: add ->poll_bio to block_device_operations

[Ming Lei]

Prepare for supporting IO polling for bio based driver.

Add ->poll_bio callback so that bio driver can provide their own logic
for polling bio.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 block/blk-core.c       | 13 +++++++++----
 block/genhd.c          |  2 ++
 include/linux/blkdev.h |  1 +
 3 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 1e24c71c6738..e585e549c291 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1113,7 +1113,8 @@ EXPORT_SYMBOL(submit_bio);
  */
 int bio_poll(struct bio *bio, unsigned int flags)
 {
-	struct request_queue *q = bio->bi_bdev->bd_disk->queue;
+	struct gendisk *disk = bio->bi_bdev->bd_disk;
+	struct request_queue *q = disk->queue;
 	blk_qc_t cookie = READ_ONCE(bio->bi_cookie);
 	int ret;
 
@@ -1125,10 +1126,14 @@ int bio_poll(struct bio *bio, unsigned int flags)
 
 	if (blk_queue_enter(q, BLK_MQ_REQ_NOWAIT))
 		return 0;
-	if (WARN_ON_ONCE(!queue_is_mq(q)))
-		ret = 0;	/* not yet implemented, should not happen */
-	else
+
+	if (queue_is_mq(q))
 		ret = blk_mq_poll(q, cookie, flags);
+	else if (disk->fops->poll_bio)
+		ret = disk->fops->poll_bio(bio, flags);
+	else
+		ret = !WARN_ON_ONCE(1);
+
 	blk_queue_exit(q);
 	return ret;
 }
diff --git a/block/genhd.c b/block/genhd.c
index 5f5628216295..3dfb7d52e280 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -471,6 +471,8 @@ static void __device_add_disk(struct device *parent, struct gendisk *disk,
 {
 	int ret;
 
+	WARN_ON_ONCE(queue_is_mq(disk->queue) && disk->fops->poll_bio);
+
 	/*
 	 * The disk queue should now be all set with enough information about
 	 * the device for the elevator code to pick an adequate default
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index fc0ba0b80776..fc63155d2ac4 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1858,6 +1858,7 @@ static inline void blk_ksm_unregister(struct request_queue *q) { }
 
 struct block_device_operations {
 	void (*submit_bio)(struct bio *bio);
+	int (*poll_bio)(struct bio *bio, unsigned int flags);
 	int (*open) (struct block_device *, fmode_t);
 	void (*release) (struct gendisk *, fmode_t);
 	int (*rw_page)(struct block_device *, sector_t, struct page *, unsigned int);
-- 
2.31.1

--
dm-devel mailing list
dm-devel@redhat.com
https://listman.redhat.com/mailman/listinfo/dm-devel

[dm-devel] [PATCH V3 3/3] dm: support bio polling

[Ming Lei]

Support bio(REQ_POLLED) polling in the following approach:

1) only support io polling on normal READ/WRITE, and other abnormal IOs
still fallback on IRQ mode, so the target io is exactly inside the dm
io.

2) hold one refcnt on io->io_count after submitting this dm bio with
REQ_POLLED

3) support dm native bio splitting, any dm io instance associated with
current bio will be added into one list which head is bio->bi_end_io
which will be recovered before ending this bio

4) implement .poll_bio() callback, call bio_poll() on the single target
bio inside the dm io which is retrieved via bio->bi_bio_drv_data; call
dec_pending() after the target io is done in .poll_bio()

4) enable QUEUE_FLAG_POLL if all underlying queues enable QUEUE_FLAG_POLL,
which is based on Jeffle's previous patch.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 drivers/md/dm-table.c |  24 ++++++++
 drivers/md/dm.c       | 131 +++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 152 insertions(+), 3 deletions(-)

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index ee47a332b462..b14b379442d2 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1491,6 +1491,12 @@ struct dm_target *dm_table_find_target(struct dm_table *t, sector_t sector)
 	return &t->targets[(KEYS_PER_NODE * n) + k];
 }
 
+static int device_not_poll_capable(struct dm_target *ti, struct dm_dev *dev,
+				   sector_t start, sector_t len, void *data)
+{
+	return !blk_queue_poll(bdev_get_queue(dev->bdev));
+}
+
 /*
  * type->iterate_devices() should be called when the sanity check needs to
  * iterate and check all underlying data devices. iterate_devices() will
@@ -1541,6 +1547,11 @@ static int count_device(struct dm_target *ti, struct dm_dev *dev,
 	return 0;
 }
 
+static int dm_table_supports_poll(struct dm_table *t)
+{
+	return !dm_table_any_dev_attr(t, device_not_poll_capable, NULL);
+}
+
 /*
  * Check whether a table has no data devices attached using each
  * target's iterate_devices method.
@@ -2078,6 +2089,19 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
 
 	dm_update_keyslot_manager(q, t);
 	blk_queue_update_readahead(q);
+
+	/*
+	 * Check for request-based device is remained to
+	 * dm_mq_init_request_queue()->blk_mq_init_allocated_queue().
+	 * For bio-based device, only set QUEUE_FLAG_POLL when all underlying
+	 * devices supporting polling.
+	 */
+	if (__table_type_bio_based(t->type)) {
+		if (dm_table_supports_poll(t))
+			blk_queue_flag_set(QUEUE_FLAG_POLL, q);
+		else
+			blk_queue_flag_clear(QUEUE_FLAG_POLL, q);
+	}
 }
 
 unsigned int dm_table_get_num_targets(struct dm_table *t)
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 363f12a285ce..cfc2e1915ec4 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -39,6 +39,8 @@
 #define DM_COOKIE_ENV_VAR_NAME "DM_COOKIE"
 #define DM_COOKIE_LENGTH 24
 
+#define REQ_SAVED_END_IO             REQ_DRV
+
 static const char *_name = DM_NAME;
 
 static unsigned int major = 0;
@@ -72,6 +74,7 @@ struct clone_info {
 	struct dm_io *io;
 	sector_t sector;
 	unsigned sector_count;
+	bool	submit_as_polled;
 };
 
 /*
@@ -99,6 +102,8 @@ struct dm_io {
 	blk_status_t status;
 	atomic_t io_count;
 	struct bio *orig_bio;
+	void	*saved_bio_end_io;
+	struct hlist_node  node;
 	unsigned long start_time;
 	spinlock_t endio_lock;
 	struct dm_stats_aux stats_aux;
@@ -687,6 +692,8 @@ static struct dm_target_io *alloc_tio(struct clone_info *ci, struct dm_target *t
 	tio->ti = ti;
 	tio->target_bio_nr = target_bio_nr;
 
+	WARN_ON_ONCE(ci->submit_as_polled && !tio->inside_dm_io);
+
 	return tio;
 }
 
@@ -938,8 +945,14 @@ static void dec_pending(struct dm_io *io, blk_status_t error)
 		end_io_acct(io);
 		free_io(md, io);
 
-		if (io_error == BLK_STS_DM_REQUEUE)
+		if (io_error == BLK_STS_DM_REQUEUE) {
+			/*
+			 * Upper layer won't help us poll split bio, so
+			 * clear REQ_POLLED in case of requeue
+			 */
+			bio->bi_opf &= ~REQ_POLLED;
 			return;
+		}
 
 		if ((bio->bi_opf & REQ_PREFLUSH) && bio->bi_iter.bi_size) {
 			/*
@@ -1366,6 +1379,9 @@ static int clone_bio(struct dm_target_io *tio, struct bio *bio,
 
 	__bio_clone_fast(clone, bio);
 
+	/* REQ_SAVED_END_IO shouldn't be inherited */
+	clone->bi_opf &= ~REQ_SAVED_END_IO;
+
 	r = bio_crypt_clone(clone, bio, GFP_NOIO);
 	if (r < 0)
 		return r;
@@ -1574,6 +1590,46 @@ static bool __process_abnormal_io(struct clone_info *ci, struct dm_target *ti,
 	return true;
 }
 
+/*
+ * Reuse ->bi_end_io as hlist head for storing all dm_io instances
+ * associated with this bio, and this bio's bi_end_io has to be
+ * stored in one of 'dm_io' instance first.
+ */
+static inline struct hlist_head *dm_get_bio_hlist_head(struct bio *bio)
+{
+	WARN_ON_ONCE(!(bio->bi_opf & REQ_SAVED_END_IO));
+	return (struct hlist_head *)&bio->bi_end_io;
+}
+
+static void dm_setup_polled_io(struct clone_info *ci)
+{
+	struct bio *bio = ci->bio;
+
+	/*
+	 * Only support bio polling for normal IO, and the target io is
+	 * exactly inside the dm io instance
+	 */
+	ci->submit_as_polled = bio->bi_opf & REQ_POLLED;
+	if (!ci->submit_as_polled)
+		return;
+
+	INIT_HLIST_NODE(&ci->io->node);
+	/*
+	 * Save .bi_end_io into dm_io, so that we can reuse .bi_end_io
+	 * for storing dm_io list
+	 */
+	if (bio->bi_opf & REQ_SAVED_END_IO) {
+		ci->io->saved_bio_end_io = NULL;
+	} else {
+		ci->io->saved_bio_end_io = bio->bi_end_io;
+		bio->bi_opf |= REQ_SAVED_END_IO;
+		INIT_HLIST_HEAD(dm_get_bio_hlist_head(bio));
+
+		/* tell block layer to poll me */
+		bio->bi_cookie = ~BLK_QC_T_NONE;
+	}
+}
+
 /*
  * Select the correct strategy for processing a non-flush bio.
  */
@@ -1590,6 +1646,8 @@ static int __split_and_process_non_flush(struct clone_info *ci)
 	if (__process_abnormal_io(ci, ti, &r))
 		return r;
 
+	dm_setup_polled_io(ci);
+
 	len = min_t(sector_t, max_io_len(ti, ci->sector), ci->sector_count);
 
 	r = __clone_and_map_data_bio(ci, ti, ci->sector, &len);
@@ -1608,6 +1666,7 @@ static void init_clone_info(struct clone_info *ci, struct mapped_device *md,
 	ci->map = map;
 	ci->io = alloc_io(md, bio);
 	ci->sector = bio->bi_iter.bi_sector;
+	ci->submit_as_polled = false;
 }
 
 #define __dm_part_stat_sub(part, field, subnd)	\
@@ -1666,8 +1725,17 @@ static void __split_and_process_bio(struct mapped_device *md,
 		}
 	}
 
-	/* drop the extra reference count */
-	dec_pending(ci.io, errno_to_blk_status(error));
+	/*
+	 * Drop the extra reference count for non-POLLED bio, and hold one
+	 * reference for POLLED bio, which will be released in dm_poll_bio
+	 *
+	 * Add every dm_io instance into the hlist_head which is stored in
+	 * bio->bi_end_io, so that dm_poll_bio can poll them all.
+	 */
+	if (!ci.submit_as_polled)
+		dec_pending(ci.io, errno_to_blk_status(error));
+	else
+		hlist_add_head(&ci.io->node, dm_get_bio_hlist_head(bio));
 }
 
 static void dm_submit_bio(struct bio *bio)
@@ -1707,6 +1775,62 @@ static void dm_submit_bio(struct bio *bio)
 	dm_put_live_table(md, srcu_idx);
 }
 
+static bool dm_poll_dm_io(struct dm_io *io, unsigned int flags)
+{
+	WARN_ON_ONCE(!io->tio.inside_dm_io);
+
+	bio_poll(&io->tio.clone, flags);
+
+	/* bio_poll holds the last reference */
+	return atomic_read(&io->io_count) == 1;
+}
+
+static int dm_poll_bio(struct bio *bio, unsigned int flags)
+{
+	struct dm_io *io;
+	void *saved_bi_end_io = NULL;
+	struct hlist_head tmp = HLIST_HEAD_INIT;
+	struct hlist_head *head = dm_get_bio_hlist_head(bio);
+	struct hlist_node *next;
+
+	/* We only poll normal bio which was marked as REQ_SAVED_END_IO */
+	if (!(bio->bi_opf & REQ_SAVED_END_IO))
+		return 0;
+
+	WARN_ON_ONCE(hlist_empty(head));
+
+	hlist_move_list(head, &tmp);
+
+	hlist_for_each_entry(io, &tmp, node) {
+		if (io->saved_bio_end_io) {
+			saved_bi_end_io = io->saved_bio_end_io;
+			break;
+		}
+	}
+
+	/* restore .bi_end_io before completing dm io */
+	WARN_ON_ONCE(!saved_bi_end_io);
+	bio->bi_opf &= ~REQ_SAVED_END_IO;
+	bio->bi_end_io = saved_bi_end_io;
+
+	hlist_for_each_entry_safe(io, next, &tmp, node) {
+		if (dm_poll_dm_io(io, flags)) {
+			hlist_del_init(&io->node);
+			dec_pending(io, 0);
+		}
+	}
+
+	/* Not done, make sure at least one dm_io stores the .bi_end_io*/
+	if (!hlist_empty(&tmp)) {
+		io = hlist_entry(tmp.first, struct dm_io, node);
+		io->saved_bio_end_io = saved_bi_end_io;
+		bio->bi_opf |= REQ_SAVED_END_IO;
+		hlist_move_list(&tmp, head);
+		return 0;
+	}
+	return 1;
+}
+
 /*-----------------------------------------------------------------
  * An IDR is used to keep track of allocated minor numbers.
  *---------------------------------------------------------------*/
@@ -3121,6 +3245,7 @@ static const struct pr_ops dm_pr_ops = {
 
 static const struct block_device_operations dm_blk_dops = {
 	.submit_bio = dm_submit_bio,
+	.poll_bio = dm_poll_bio,
 	.open = dm_blk_open,
 	.release = dm_blk_close,
 	.ioctl = dm_blk_ioctl,
-- 
2.31.1

--
dm-devel mailing list
dm-devel@redhat.com
https://listman.redhat.com/mailman/listinfo/dm-devel

Re: [dm-devel] [PATCH V3 0/3] block/dm: support bio polling

[Mike Snitzer]

On Wed, Jun 23 2021 at  3:40P -0400,
Ming Lei <ming.lei@redhat.com> wrote:

> Hello Guys,
> 
> Based on Christoph's bio based polling model[1], implement DM bio polling
> with one very simple approach.
> 
> Patch 1 adds helper of blk_queue_poll().
> 
> Patch 2 adds .bio_poll() callback to block_device_operations, so bio
> driver can implement its own logic for io polling.
> 
> Patch 3 implements bio polling for device mapper.
> 
> 
> V3:
> 	- patch style change as suggested by Christoph(2/3)
> 	- fix kernel panic issue caused by nested dm polling, which is found
> 	  & figured out by Jeffle Xu (3/3)
> 	- re-organize setup polling code (3/3)
> 	- remove RFC
> 
> V2:
> 	- drop patch to add new fields into bio
> 	- support io polling for dm native bio splitting
> 	- add comment
> 
> Ming Lei (3):
>   block: add helper of blk_queue_poll
>   block: add ->poll_bio to block_device_operations
>   dm: support bio polling
> 
>  block/blk-core.c         |  18 +++---
>  block/blk-sysfs.c        |   4 +-
>  block/genhd.c            |   2 +
>  drivers/md/dm-table.c    |  24 +++++++
>  drivers/md/dm.c          | 131 ++++++++++++++++++++++++++++++++++++++-
>  drivers/nvme/host/core.c |   2 +-
>  include/linux/blkdev.h   |   2 +
>  7 files changed, 170 insertions(+), 13 deletions(-)
> 
> -- 
> 2.31.1
> 

Hey Ming,

I'd like us to follow-through with adding bio-based polling support.
Kind of strange none of us that were sent this V3 ever responded,
sorry about that!

Do you have interest in rebasing this patchset (against linux-dm.git's
"dm-5.18" branch since there has been quite some churn)?  Or are you
OK with me doing the rebase?

thanks,
Mike

--
dm-devel mailing list
dm-devel@redhat.com
https://listman.redhat.com/mailman/listinfo/dm-devel

Re: [dm-devel] [PATCH V3 0/3] block/dm: support bio polling

[Ming Lei]

On Mon, Feb 28, 2022 at 11:27:44AM -0500, Mike Snitzer wrote:
> On Wed, Jun 23 2021 at  3:40P -0400,
> Ming Lei <ming.lei@redhat.com> wrote:
> 
> > Hello Guys,
> > 
> > Based on Christoph's bio based polling model[1], implement DM bio polling
> > with one very simple approach.
> > 
> > Patch 1 adds helper of blk_queue_poll().
> > 
> > Patch 2 adds .bio_poll() callback to block_device_operations, so bio
> > driver can implement its own logic for io polling.
> > 
> > Patch 3 implements bio polling for device mapper.
> > 
> > 
> > V3:
> > 	- patch style change as suggested by Christoph(2/3)
> > 	- fix kernel panic issue caused by nested dm polling, which is found
> > 	  & figured out by Jeffle Xu (3/3)
> > 	- re-organize setup polling code (3/3)
> > 	- remove RFC
> > 
> > V2:
> > 	- drop patch to add new fields into bio
> > 	- support io polling for dm native bio splitting
> > 	- add comment
> > 
> > Ming Lei (3):
> >   block: add helper of blk_queue_poll
> >   block: add ->poll_bio to block_device_operations
> >   dm: support bio polling
> > 
> >  block/blk-core.c         |  18 +++---
> >  block/blk-sysfs.c        |   4 +-
> >  block/genhd.c            |   2 +
> >  drivers/md/dm-table.c    |  24 +++++++
> >  drivers/md/dm.c          | 131 ++++++++++++++++++++++++++++++++++++++-
> >  drivers/nvme/host/core.c |   2 +-
> >  include/linux/blkdev.h   |   2 +
> >  7 files changed, 170 insertions(+), 13 deletions(-)
> > 
> > -- 
> > 2.31.1
> > 
> 
> Hey Ming,
> 
> I'd like us to follow-through with adding bio-based polling support.
> Kind of strange none of us that were sent this V3 ever responded,
> sorry about that!
> 
> Do you have interest in rebasing this patchset (against linux-dm.git's
> "dm-5.18" branch since there has been quite some churn)?  Or are you
> OK with me doing the rebase?

Hi Mike,

Actually I have one local v5.17 rebase:

https://github.com/ming1/linux/tree/my_v5.17-dm-io-poll

Also one for-5.18/block rebase which is done just now:

https://github.com/ming1/linux/tree/my_v5.18-dm-bio-poll

In my previous test on v5.17 rebase, the IOPS improvement is a bit small,
so I didn't post it out. Recently not get time to investigate
the performance further, so please feel free to work on it.


Thanks,
Ming

--
dm-devel mailing list
dm-devel@redhat.com
https://listman.redhat.com/mailman/listinfo/dm-devel

Re: [dm-devel] [PATCH V3 0/3] block/dm: support bio polling

[Mike Snitzer]

On Mon, Feb 28 2022 at  7:58P -0500,
Ming Lei <ming.lei@redhat.com> wrote:

> On Mon, Feb 28, 2022 at 11:27:44AM -0500, Mike Snitzer wrote:
> > 
> > Hey Ming,
> > 
> > I'd like us to follow-through with adding bio-based polling support.
> > Kind of strange none of us that were sent this V3 ever responded,
> > sorry about that!
> > 
> > Do you have interest in rebasing this patchset (against linux-dm.git's
> > "dm-5.18" branch since there has been quite some churn)?  Or are you
> > OK with me doing the rebase?
> 
> Hi Mike,
> 
> Actually I have one local v5.17 rebase:
> 
> https://github.com/ming1/linux/tree/my_v5.17-dm-io-poll
> 
> Also one for-5.18/block rebase which is done just now:
> 
> https://github.com/ming1/linux/tree/my_v5.18-dm-bio-poll
> 
> In my previous test on v5.17 rebase, the IOPS improvement is a bit small,
> so I didn't post it out. Recently not get time to investigate
> the performance further, so please feel free to work on it.

OK, I've rebased it on dm-5.18.

Can you please share the exact test(s) you were running?  I assume you
were running directly against a request-based device and then
comparing polling perf through dm-linear to the same underlying
request-based device?

Thanks,
Mike

--
dm-devel mailing list
dm-devel@redhat.com
https://listman.redhat.com/mailman/listinfo/dm-devel

Re: [dm-devel] [PATCH V3 0/3] block/dm: support bio polling

[Ming Lei]

On Tue, Mar 01, 2022 at 04:19:42PM -0500, Mike Snitzer wrote:
> On Mon, Feb 28 2022 at  7:58P -0500,
> Ming Lei <ming.lei@redhat.com> wrote:
> 
> > On Mon, Feb 28, 2022 at 11:27:44AM -0500, Mike Snitzer wrote:
> > > 
> > > Hey Ming,
> > > 
> > > I'd like us to follow-through with adding bio-based polling support.
> > > Kind of strange none of us that were sent this V3 ever responded,
> > > sorry about that!
> > > 
> > > Do you have interest in rebasing this patchset (against linux-dm.git's
> > > "dm-5.18" branch since there has been quite some churn)?  Or are you
> > > OK with me doing the rebase?
> > 
> > Hi Mike,
> > 
> > Actually I have one local v5.17 rebase:
> > 
> > https://github.com/ming1/linux/tree/my_v5.17-dm-io-poll
> > 
> > Also one for-5.18/block rebase which is done just now:
> > 
> > https://github.com/ming1/linux/tree/my_v5.18-dm-bio-poll
> > 
> > In my previous test on v5.17 rebase, the IOPS improvement is a bit small,
> > so I didn't post it out. Recently not get time to investigate
> > the performance further, so please feel free to work on it.
> 
> OK, I've rebased it on dm-5.18.
> 
> Can you please share the exact test(s) you were running?  I assume you
> were running directly against a request-based device and then
> comparing polling perf through dm-linear to the same underlying
> request-based device?

I run io_uring over dm-linear and dm-stripe, over two nvme disks with
2 poll_queues.

IOPS improvement can be observed, but not big.

Thanks,
Ming

--
dm-devel mailing list
dm-devel@redhat.com
https://listman.redhat.com/mailman/listinfo/dm-devel