[dm-devel] [PATCH v2 6/6] dm: remove the pending IO accounting
Mike Snitzer
snitzer at redhat.com
Fri Nov 30 22:22:26 UTC 2018
From: Mikulas Patocka <mpatocka at redhat.com>
Remove the "pending" atomic counters, that duplicate block-core's
in_flight counters, and update md_in_flight() to look at percpu
in_flight counters.
Signed-off-by: Mikulas Patocka <mpatocka at redhat.com>
Signed-off-by: Mike Snitzer <snitzer at redhat.com>
---
drivers/md/dm-core.h | 2 --
drivers/md/dm.c | 34 +++++++++++++++-------------------
2 files changed, 15 insertions(+), 21 deletions(-)
diff --git a/drivers/md/dm-core.h b/drivers/md/dm-core.h
index 224d44503a06..6fe883fac471 100644
--- a/drivers/md/dm-core.h
+++ b/drivers/md/dm-core.h
@@ -65,7 +65,6 @@ struct mapped_device {
*/
struct work_struct work;
wait_queue_head_t wait;
- atomic_t pending[2];
spinlock_t deferred_lock;
struct bio_list deferred;
@@ -119,7 +118,6 @@ struct mapped_device {
struct srcu_struct io_barrier;
};
-int md_in_flight(struct mapped_device *md);
void disable_write_same(struct mapped_device *md);
void disable_write_zeroes(struct mapped_device *md);
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index a8ae7931bce7..ff6e5a5902f2 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -646,25 +646,30 @@ static void free_tio(struct dm_target_io *tio)
bio_put(&tio->clone);
}
-int md_in_flight(struct mapped_device *md)
+static bool md_in_flight(struct mapped_device *md)
{
- return atomic_read(&md->pending[READ]) +
- atomic_read(&md->pending[WRITE]);
+ int cpu;
+ struct hd_struct *part = &dm_disk(md)->part0;
+
+ for_each_possible_cpu(cpu) {
+ if (local_read(&per_cpu_ptr(part->dkstats, cpu)->in_flight[0]) ||
+ local_read(&per_cpu_ptr(part->dkstats, cpu)->in_flight[1]))
+ return true;
+ }
+
+ return false;
}
static void start_io_acct(struct dm_io *io)
{
struct mapped_device *md = io->md;
struct bio *bio = io->orig_bio;
- int rw = bio_data_dir(bio);
io->start_time = jiffies;
generic_start_io_acct(md->queue, bio_op(bio), bio_sectors(bio),
&dm_disk(md)->part0);
- atomic_inc(&md->pending[rw]);
-
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),
@@ -676,8 +681,6 @@ static void end_io_acct(struct dm_io *io)
struct mapped_device *md = io->md;
struct bio *bio = io->orig_bio;
unsigned long duration = jiffies - io->start_time;
- int pending;
- int rw = bio_data_dir(bio);
generic_end_io_acct(md->queue, bio_op(bio), &dm_disk(md)->part0,
io->start_time);
@@ -687,16 +690,11 @@ static void end_io_acct(struct dm_io *io)
bio->bi_iter.bi_sector, bio_sectors(bio),
true, duration, &io->stats_aux);
- /*
- * After this is decremented the bio must not be touched if it is
- * a flush.
- */
- pending = atomic_dec_return(&md->pending[rw]);
- pending += atomic_read(&md->pending[rw^0x1]);
-
/* nudge anyone waiting on suspend queue */
- if (!pending)
- wake_up(&md->wait);
+ if (unlikely(waitqueue_active(&md->wait))) {
+ if (!md_in_flight(md))
+ wake_up(&md->wait);
+ }
}
/*
@@ -1904,8 +1902,6 @@ static struct mapped_device *alloc_dev(int minor)
if (!md->disk)
goto bad;
- atomic_set(&md->pending[0], 0);
- atomic_set(&md->pending[1], 0);
init_waitqueue_head(&md->wait);
INIT_WORK(&md->work, dm_wq_work);
init_waitqueue_head(&md->eventq);
--
2.15.0
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