From: Jens Axboe <[email protected]>
To: [email protected]
Cc: [email protected], [email protected]
Subject: Re: [PATCH] io-wq: set task TASK_INTERRUPTIBLE state before schedule_timeout
Date: Tue, 27 Oct 2020 07:35:00 -0600 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
On 10/26/20 9:09 PM, [email protected] wrote:
> From: Zqiang <[email protected]>
>
> In 'io_wqe_worker' thread, if the work which in 'wqe->work_list' be
> finished, the 'wqe->work_list' is empty, and after that the
> '__io_worker_idle' func return false, the task state is TASK_RUNNING,
> need to be set TASK_INTERRUPTIBLE before call schedule_timeout func.
I don't think that's safe - what if someone added work right before you
call schedule_timeout_interruptible? Something ala:
io_wq_enqueue()
set_current_state(TASK_INTERRUPTIBLE();
schedule_timeout(WORKER_IDLE_TIMEOUT);
then we'll have work added and the task state set to running, but the
worker itself just sets us to non-running and will hence wait
WORKER_IDLE_TIMEOUT before the work is processed.
The current situation will do one extra loop for this case, as the
schedule_timeout() just ends up being a nop and we go around again
checking for work. Since we already unused the mm, the next iteration
will go to sleep properly unless new work came in.
--
Jens Axboe
next prev parent reply other threads:[~2020-10-27 13:35 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-27 3:09 [PATCH] io-wq: set task TASK_INTERRUPTIBLE state before schedule_timeout qiang.zhang
2020-10-27 13:35 ` Jens Axboe [this message]
2020-10-28 2:47 ` 回复: " Zhang, Qiang
2020-10-28 13:36 ` Jens Axboe
-- strict thread matches above, loose matches on Subject: below --
2020-10-27 3:06 qiang.zhang
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