From: Jens Axboe <axboe@kernel.dk>
To: Dylan Yudaken <dylany@fb.com>,
"asml.silence@gmail.com" <asml.silence@gmail.com>,
"io-uring@vger.kernel.org" <io-uring@vger.kernel.org>
Subject: Re: [PATCH for-next] io_uring: fix CQE reordering
Date: Fri, 23 Sep 2022 08:34:11 -0600 [thread overview]
Message-ID: <c99a97af-5d1d-03d8-40cf-677a2b1027c3@kernel.dk> (raw)
In-Reply-To: <2815cf233c3171204823eda9a18f7c67894b7db9.camel@fb.com>
On 9/23/22 8:32 AM, Dylan Yudaken wrote:
> On Fri, 2022-09-23 at 14:53 +0100, Pavel Begunkov wrote:
>> Overflowing CQEs may result in reordeing, which is buggy in case of
>> links, F_MORE and so.
>>
>
> Maybe the commit message got cut off?
>
>
> I think this is probably ok, the downside being that CQE's with no
> ordering constraints will have ordering forced on them. An alternative
> would be for each case (eg linked, zerocopy, multishot) to either pause
> or force CQE's to be overflow ones. This wouldnt slow down the other
> codepaths. I don't have an idea for how difficult this might be.
I don't think this matters at all. If you hit overflow, things are
screwed and slow anyway. Doesn't make sense to optimize for that path,
so we may as well impose ordering for everything at that point.
--
Jens Axboe
next prev parent reply other threads:[~2022-09-23 14:34 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-23 13:53 [PATCH for-next] io_uring: fix CQE reordering Pavel Begunkov
2022-09-23 14:19 ` Jens Axboe
2022-09-23 14:26 ` Pavel Begunkov
2022-09-23 14:35 ` Jens Axboe
2022-09-23 14:43 ` Pavel Begunkov
2022-09-23 14:51 ` Jens Axboe
2022-09-23 14:32 ` Dylan Yudaken
2022-09-23 14:34 ` Jens Axboe [this message]
2022-09-23 21:05 ` Jens Axboe
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