From: Jens Axboe <axboe@kernel.dk>
To: Pavel Begunkov <asml.silence@gmail.com>, io-uring@vger.kernel.org
Subject: Re: [PATCH 2/4] io_uring: patch up IOPOLL overflow_flush sync
Date: Sun, 3 Jan 2021 15:05:53 -0700 [thread overview]
Message-ID: <f82471b3-3302-7963-6f9e-f6ee0e56bd7c@kernel.dk> (raw)
In-Reply-To: <0c1a302a-eec0-6de1-2b6e-c06739d4c70a@gmail.com>
On 1/3/21 9:29 AM, Pavel Begunkov wrote:
> On 03/01/2021 15:12, Jens Axboe wrote:
>> On 1/2/21 9:06 AM, Pavel Begunkov wrote:
>>> IOPOLL skips completion locking but keeps it under uring_lock, thus
>>> io_cqring_overflow_flush() and so io_cqring_events() need extra care.
>>> Add extra conditional locking around them.
>>
>> This one is pretty ugly. Would be greatly preferable to grab the lock
>> higher up instead of passing down the need to do so, imho.
> I can't disagree with that, the whole iopoll locking is a mess, but
> still don't want to penalise SQPOLL|IOPOLL.
>
> Splitting flushing from cqring_events might be a good idea. How
> about the one below (not tested)? Killing this noflush looks even
> cleaner than before.
From a quick look, that's much better.
--
Jens Axboe
next prev parent reply other threads:[~2021-01-03 22:06 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-02 16:06 [PATCH 0/4] bunch of random fixes Pavel Begunkov
2021-01-02 16:06 ` [PATCH 1/4] io_uring: dont kill fasync under completion_lock Pavel Begunkov
2021-01-03 11:58 ` Pavel Begunkov
2021-01-02 16:06 ` [PATCH 2/4] io_uring: patch up IOPOLL overflow_flush sync Pavel Begunkov
2021-01-03 15:12 ` Jens Axboe
2021-01-03 16:29 ` Pavel Begunkov
2021-01-03 22:05 ` Jens Axboe [this message]
2021-01-02 16:06 ` [PATCH 3/4] io_uring: drop file refs after task cancel Pavel Begunkov
2021-01-02 16:06 ` [PATCH 4/4] io_uring: cancel more aggressively in exit_work Pavel Begunkov
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