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From: Jens Axboe <[email protected]>
To: Pavel Begunkov <[email protected]>, [email protected]
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: <[email protected]> (raw)
In-Reply-To: <[email protected]>

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


  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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