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md/raid10: prevent unnecessary calls to wake_up() in fast path

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Currently, wake_up() is called unconditionally in fast path such as
raid10_make_request(), which will cause lock contention under high
concurrency:

raid10_make_request
 wake_up
  __wake_up_common_lock
   spin_lock_irqsave

Improve performance by only call wake_up() if waitqueue is not empty
in allow_barrier() and raid10_make_request().

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Acked-by: Guoqing Jiang <guoqing.jiang@linux.dev>
Signed-off-by: Song Liu <song@kernel.org>
This commit is contained in:
Yu Kuai 2022-09-16 19:34:26 +08:00 • committed by Song Liu
parent 0de57e541b
commit 0c0be98bbe
1 changed files with 8 additions and 2 deletions
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10
drivers/md/raid10.c
View file

@ -274,6 +274,12 @@ static void put_buf(struct r10bio *r10_bio)
lower_barrier(conf); lower_barrier(conf);
} }
static void wake_up_barrier(struct r10conf *conf)
{
if (wq_has_sleeper(&conf->wait_barrier))
wake_up(&conf->wait_barrier);
}
static void reschedule_retry(struct r10bio *r10_bio) static void reschedule_retry(struct r10bio *r10_bio)
{ {
unsigned long flags; unsigned long flags;
@ -1015,7 +1021,7 @@ static void allow_barrier(struct r10conf *conf)
{ {
if ((atomic_dec_and_test(&conf->nr_pending)) || if ((atomic_dec_and_test(&conf->nr_pending)) ||
(conf->array_freeze_pending)) (conf->array_freeze_pending))
wake_up(&conf->wait_barrier); wake_up_barrier(conf);
} }
static void freeze_array(struct r10conf *conf, int extra) static void freeze_array(struct r10conf *conf, int extra)
@ -1891,7 +1897,7 @@ static bool raid10_make_request(struct mddev *mddev, struct bio *bio)
__make_request(mddev, bio, sectors); __make_request(mddev, bio, sectors);
/* In case raid10d snuck in to freeze_array */ /* In case raid10d snuck in to freeze_array */
wake_up(&conf->wait_barrier); wake_up_barrier(conf);
return true; return true;
} }