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From: Oleg Nesterov <oleg@redhat.com>
To: Josef Bacik <josef@toxicpanda.com>
Cc: axboe@kernel.dk, linux-block@vger.kernel.org, kernel-team@fb.com,
	peterz@infradead.org
Subject: Re: [PATCH 4/4] rq-qos: don't reset has_sleepers on spurious wakeups
Date: Tue, 16 Jul 2019 10:35:26 +0200	[thread overview]
Message-ID: <20190716083526.GB15528@redhat.com> (raw)
In-Reply-To: <20190715201120.72749-5-josef@toxicpanda.com>

On 07/15, Josef Bacik wrote:
>
> If we had multiple sleepers before we don't need to worry about never
> being woken up.  If we're woken up randomly without having gotten our
> inflight token then we need to go back to sleep, we won't be properly
> woken up without being given our inflight token anyway so this resetting
> isn't needed.

Yes, and this means that we can avoid acquire_inflight_cb() if e're woken
up randomly, so

> Signed-off-by: Josef Bacik <josef@toxicpanda.com>
> ---
>  block/blk-rq-qos.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/block/blk-rq-qos.c b/block/blk-rq-qos.c
> index f4aa7b818cf5..35bc6f54d088 100644
> --- a/block/blk-rq-qos.c
> +++ b/block/blk-rq-qos.c
> @@ -261,7 +261,6 @@ void rq_qos_wait(struct rq_wait *rqw, void *private_data,
>  			break;
>  		}
>  		io_schedule();
> -		has_sleeper = false;

I still think it should do

		has_sleeper = true;

Oleg.


  reply	other threads:[~2019-07-16  8:35 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-15 20:11 [PATCH 0/4][v2] rq-qos memory barrier shenanigans Josef Bacik
2019-07-15 20:11 ` [PATCH 1/4] wait: add wq_has_single_sleeper helper Josef Bacik
2019-07-15 20:11 ` [PATCH 2/4] rq-qos: fix missed wake-ups in rq_qos_throttle Josef Bacik
2019-07-15 20:11 ` [PATCH 3/4] rq-qos: use READ_ONCE/WRITE_ONCE for got_token Josef Bacik
2019-07-16  8:29   ` Oleg Nesterov
2019-07-15 20:11 ` [PATCH 4/4] rq-qos: don't reset has_sleepers on spurious wakeups Josef Bacik
2019-07-16  8:35   ` Oleg Nesterov [this message]
2019-07-16  8:39 ` [PATCH 0/4][v2] rq-qos memory barrier shenanigans Oleg Nesterov

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