[PATCH v3 3/5] md/raid10: prevent unnecessary calls to wake_up() in fast path
From: Yu Kuai <hidden>
Date: 2022-09-16 11:23:50
Also in:
lkml
Subsystem:
software raid (multiple disks) support, the rest · Maintainers:
Song Liu, Yu Kuai, Linus Torvalds
From: Yu Kuai <redacted> 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 <redacted> --- 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