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From: Jens Axboe <axboe@kernel.dk>
To: Pavel Begunkov <asml.silence@gmail.com>,
	io-uring <io-uring@vger.kernel.org>
Subject: Re: [PATCH] io_uring: trigger worker exit when ring is exiting
Date: Thu, 2 Sep 2021 12:19:25 -0600	[thread overview]
Message-ID: <ee782e1d-ae8f-264c-bd21-4e0c496ece99@kernel.dk> (raw)
In-Reply-To: <0d9cf759-98fc-334a-e6ab-c9605dc3a8af@kernel.dk>

On 9/2/21 12:08 PM, Jens Axboe wrote:
> On 9/2/21 12:04 PM, Pavel Begunkov wrote:
>> On 9/2/21 6:56 PM, Jens Axboe wrote:
>>> If a task exits normally, then the teardown of async workers happens
>>> quickly. But if it simply closes the ring fd, then the async teardown
>>> ends up waiting for workers to timeout if they are sleeping, which can
>>> then take up to 5 seconds (by default). This isn't a big issue as this
>>> happens off the workqueue path, but let's be nicer and ensure that we
>>> exit as quick as possible.
>>
>> ring = io_uring_init();
>> ...
>> io_uring_close(&ring); // triggers io_ring_ctx_wait_and_kill()
>> rint2 = io_uring_init();
>> ...
>>
>> It looks IO_WQ_BIT_EXIT there will be troublesome.
> 
> I wonder if we can get by with just a wakeup. Let me test...

Nah not enough. Would be nice to fix though, pretty annoying that the
threads sit there for 5 seconds doing nothing.

-- 
Jens Axboe


      reply	other threads:[~2021-09-02 18:19 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-02 17:56 Jens Axboe
2021-09-02 18:04 ` Pavel Begunkov
2021-09-02 18:08   ` Jens Axboe
2021-09-02 18:19     ` Jens Axboe [this message]

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