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dm: support turning off block-core's io stats accounting

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Commit bc58ba9468 ("block: add sysfs file for controlling io stats
accounting") allowed users to turn off disk stat accounting completely
by checking if queue flag QUEUE_FLAG_IO_STAT is set. In dm, this flag
is neither set nor checked: so block-core's io stats are continuously
counted and cannot be turned off.

Add support for turning off block-core's io stats accounting for dm.
Set QUEUE_FLAG_IO_STAT for dm's request_queue. If QUEUE_FLAG_IO_STAT
is set when an io starts, record the need for block core's io stats by
setting the DM_IO_BLK_STAT dm_io flag to avoid io stats being disabled
in the middle of the io.

DM statistics (dm-stats) is independent of block-core's io stats and
remains unchanged.

Signed-off-by: Li Nan <linan122@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
This commit is contained in:
Li Nan 2023-06-13 09:33:32 +08:00 committed by Mike Snitzer
parent e118029cb7
commit 526d10061b
2 changed files with 13 additions and 6 deletions
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3
drivers/md/dm-core.h
View File

@ -306,7 +306,8 @@ struct dm_io {
*/
enum {
DM_IO_ACCOUNTED,
DM_IO_WAS_SPLIT
DM_IO_WAS_SPLIT,
DM_IO_BLK_STAT
};
static inline bool dm_io_flagged(struct dm_io *io, unsigned int bit)

16
drivers/md/dm.c
View File

@ -511,11 +511,14 @@ static void dm_io_acct(struct dm_io *io, bool end)
else
sectors = io->sectors;
if (!end)
bdev_start_io_acct(bio->bi_bdev, bio_op(bio), start_time);
else
bdev_end_io_acct(bio->bi_bdev, bio_op(bio), sectors,
start_time);
if (dm_io_flagged(io, DM_IO_BLK_STAT)) {
if (!end)
bdev_start_io_acct(bio->bi_bdev, bio_op(bio),
start_time);
else
bdev_end_io_acct(bio->bi_bdev, bio_op(bio),
sectors, start_time);
}
if (static_branch_unlikely(&stats_enabled) &&
unlikely(dm_stats_used(&md->stats))) {
@ -592,6 +595,8 @@ static struct dm_io *alloc_io(struct mapped_device *md, struct bio *bio)
spin_lock_init(&io->lock);
io->start_time = jiffies;
io->flags = 0;
if (blk_queue_io_stat(md->queue))
dm_io_set_flag(io, DM_IO_BLK_STAT);
if (static_branch_unlikely(&stats_enabled))
dm_stats_record_start(&md->stats, &io->stats_aux);
@ -2341,6 +2346,7 @@ int dm_setup_md_queue(struct mapped_device *md, struct dm_table *t)
break;
case DM_TYPE_BIO_BASED:
case DM_TYPE_DAX_BIO_BASED:
blk_queue_flag_set(QUEUE_FLAG_IO_STAT, md->queue);
break;
case DM_TYPE_NONE:
WARN_ON_ONCE(true);