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From: Mike Snitzer <snitzer@redhat.com>
To: axboe@kernel.dk
Cc: linux-block@vger.kernel.org, dm-devel@redhat.com, hch@lst.de
Subject: [dm-devel] [PATCH v4 3/3] dm: properly fix redundant bio-based IO accounting
Date: Fri, 28 Jan 2022 10:58:41 -0500	[thread overview]
Message-ID: <20220128155841.39644-4-snitzer@redhat.com> (raw)
In-Reply-To: <20220128155841.39644-1-snitzer@redhat.com>

Record the start_time for a bio but defer the starting block core's IO
accounting until after IO is submitted using bio_start_io_acct_time().

This approach avoids the need to mess around with any of the
individual IO stats in response to a bio_split() that follows bio
submission.

Reported-by: Bud Brown <bubrown@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: stable@vger.kernel.org
Depends-on: 1073e8492f88 ("block: add bio_start_io_acct_time() to control start_time")
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
---
 drivers/md/dm.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 9849114b3c08..dcbd6d201619 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -489,7 +489,7 @@ static void start_io_acct(struct dm_io *io)
 	struct mapped_device *md = io->md;
 	struct bio *bio = io->orig_bio;
 
-	io->start_time = bio_start_io_acct(bio);
+	bio_start_io_acct_time(bio, io->start_time);
 	if (unlikely(dm_stats_used(&md->stats)))
 		dm_stats_account_io(&md->stats, bio_data_dir(bio),
 				    bio->bi_iter.bi_sector, bio_sectors(bio),
@@ -535,7 +535,7 @@ static struct dm_io *alloc_io(struct mapped_device *md, struct bio *bio)
 	io->md = md;
 	spin_lock_init(&io->endio_lock);
 
-	start_io_acct(io);
+	io->start_time = jiffies;
 
 	return io;
 }
@@ -1482,6 +1482,7 @@ static void __split_and_process_bio(struct mapped_device *md,
 			submit_bio_noacct(bio);
 		}
 	}
+	start_io_acct(ci.io);
 
 	/* drop the extra reference count */
 	dm_io_dec_pending(ci.io, errno_to_blk_status(error));
-- 
2.15.0

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


WARNING: multiple messages have this Message-ID (diff)
From: Mike Snitzer <snitzer@redhat.com>
To: axboe@kernel.dk
Cc: hch@lst.de, dm-devel@redhat.com, linux-block@vger.kernel.org
Subject: [PATCH v4 3/3] dm: properly fix redundant bio-based IO accounting
Date: Fri, 28 Jan 2022 10:58:41 -0500	[thread overview]
Message-ID: <20220128155841.39644-4-snitzer@redhat.com> (raw)
In-Reply-To: <20220128155841.39644-1-snitzer@redhat.com>

Record the start_time for a bio but defer the starting block core's IO
accounting until after IO is submitted using bio_start_io_acct_time().

This approach avoids the need to mess around with any of the
individual IO stats in response to a bio_split() that follows bio
submission.

Reported-by: Bud Brown <bubrown@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: stable@vger.kernel.org
Depends-on: 1073e8492f88 ("block: add bio_start_io_acct_time() to control start_time")
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
---
 drivers/md/dm.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 9849114b3c08..dcbd6d201619 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -489,7 +489,7 @@ static void start_io_acct(struct dm_io *io)
 	struct mapped_device *md = io->md;
 	struct bio *bio = io->orig_bio;
 
-	io->start_time = bio_start_io_acct(bio);
+	bio_start_io_acct_time(bio, io->start_time);
 	if (unlikely(dm_stats_used(&md->stats)))
 		dm_stats_account_io(&md->stats, bio_data_dir(bio),
 				    bio->bi_iter.bi_sector, bio_sectors(bio),
@@ -535,7 +535,7 @@ static struct dm_io *alloc_io(struct mapped_device *md, struct bio *bio)
 	io->md = md;
 	spin_lock_init(&io->endio_lock);
 
-	start_io_acct(io);
+	io->start_time = jiffies;
 
 	return io;
 }
@@ -1482,6 +1482,7 @@ static void __split_and_process_bio(struct mapped_device *md,
 			submit_bio_noacct(bio);
 		}
 	}
+	start_io_acct(ci.io);
 
 	/* drop the extra reference count */
 	dm_io_dec_pending(ci.io, errno_to_blk_status(error));
-- 
2.15.0


  parent reply	other threads:[~2022-01-28 15:59 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-28 15:58 [PATCH v4 0/3] block/dm: fix bio-based DM IO accounting Mike Snitzer
2022-01-28 15:58 ` [dm-devel] " Mike Snitzer
2022-01-28 15:58 ` [dm-devel] [PATCH v4 1/3] block: add bio_start_io_acct_time() to control start_time Mike Snitzer
2022-01-28 15:58   ` Mike Snitzer
2022-01-28 15:58 ` [PATCH v4 2/3] dm: revert partial fix for redundant bio-based IO accounting Mike Snitzer
2022-01-28 15:58   ` [dm-devel] " Mike Snitzer
2022-01-28 15:58 ` Mike Snitzer [this message]
2022-01-28 15:58   ` [PATCH v4 3/3] dm: properly fix " Mike Snitzer
2022-01-28 17:19 ` [dm-devel] [PATCH v4 0/3] block/dm: fix bio-based DM " Jens Axboe
2022-01-28 17:19   ` Jens Axboe

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