Messages in this thread | | | Subject | Re: [PATCH v3 3/5] md/raid10: prevent unnecessary calls to wake_up() in fast path | From | Guoqing Jiang <> | Date | Sun, 18 Sep 2022 19:38:50 +0800 |
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On 9/16/22 7:34 PM, Yu Kuai wrote: > From: Yu Kuai <yukuai3@huawei.com> > > 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> > --- > 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; > } >
Acked-by: Guoqing Jiang <guoqing.jiang@linux.dev>
Thanks, Guoqing
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