From: Yu Kuai <yukuai3@xxxxxxxxxx>
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@xxxxxxxxxx>
---
drivers/md/raid10.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index df435d693637..cf452c25e1e5 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -274,6 +274,12 @@ static void put_buf(struct r10bio *r10_bio)
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)
{
unsigned long flags;
@@ -1015,7 +1021,7 @@ static void allow_barrier(struct r10conf *conf)
{
if ((atomic_dec_and_test(&conf->nr_pending)) ||
(conf->array_freeze_pending))
- wake_up(&conf->wait_barrier);
+ wake_up_barrier(conf);
}
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);
/* In case raid10d snuck in to freeze_array */
- wake_up(&conf->wait_barrier);
+ wake_up_barrier(conf);
return true;
}
--
2.31.1
