From: Pavel Begunkov <asml.silence@gmail.com>
To: Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] io_uring: remove wait loop spurious wakeups
Date: Tue, 8 Oct 2019 19:43:16 +0300 [thread overview]
Message-ID: <d035bb1b-e6f0-77db-a434-1761b0a7a142@gmail.com> (raw)
In-Reply-To: <e11a0716-eb18-4ce3-9902-3247beafe65a@kernel.dk>
[-- Attachment #1.1: Type: text/plain, Size: 834 bytes --]
On 08/10/2019 06:16, Jens Axboe wrote:
> On 10/7/19 5:18 PM, Pavel Begunkov (Silence) wrote:
>> From: Pavel Begunkov <asml.silence@gmail.com>
>>
>> Any changes interesting to tasks waiting in io_cqring_wait() are
>> commited with io_cqring_ev_posted(). However, io_ring_drop_ctx_refs()
>> also tries to do that but with no reason, that means spurious wakeups
>> every io_free_req() and io_uring_enter().
>>
>> Just use percpu_ref_put() instead.
>
> Looks good, this is a leftover from when the ctx teardown used
> the waitqueue as well.
>
BTW, is there a reason for ref-counting in struct io_kiocb? I understand
the idea behind submission reference, but don't see any actual part
needing it.
Tested with another ref-counting patch and got +5-8% to
nops performance.
--
Yours sincerely,
Pavel Begunkov
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 833 bytes --]
next prev parent reply other threads:[~2019-10-08 16:43 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-07 23:18 Pavel Begunkov (Silence)
2019-10-08 3:16 ` Jens Axboe
2019-10-08 16:43 ` Pavel Begunkov [this message]
2019-10-08 17:00 ` Jens Axboe
2019-10-08 20:58 ` Pavel Begunkov
2019-10-08 21:22 ` Jens Axboe
2019-10-08 22:05 ` Pavel Begunkov
2019-10-09 2:54 ` Jens Axboe
2019-10-09 9:19 ` Pavel Begunkov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=d035bb1b-e6f0-77db-a434-1761b0a7a142@gmail.com \
--to=asml.silence@gmail.com \
--cc=axboe@kernel.dk \
--cc=linux-block@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
Powered by JetHome