From: Jens Axboe <axboe@kernel.dk>
To: Pavel Begunkov <asml.silence@gmail.com>, io-uring@vger.kernel.org
Subject: Re: [PATCH 3/5] io_uring: don't put a poll req under spinlock
Date: Tue, 13 Oct 2020 08:54:10 -0600 [thread overview]
Message-ID: <04f2d94c-0e75-b251-e244-b7ac95863862@kernel.dk> (raw)
In-Reply-To: <a723ec3fb07e906f28631d3a67b4d125b513b9ee.1602577875.git.asml.silence@gmail.com>
On 10/13/20 2:43 AM, Pavel Begunkov wrote:
> Move io_put_req() in io_poll_task_handler() from under spinlock. That's
> a good rule to minimise time within spinlock sections, and
> performance-wise it should affect only rare cases/slow-path.
It's actually more important not to bounce on the lock, especially
when the extra path isn't that long. You'll end up with the same hold
time, just split, but the downside is that you'll dirty that lock twice
instead of one.
So while I think the patch is fine as it avoids REQ_F_COMP_LOCKED,
I don't think the commit message really reflects reality. I'll
adjust it a bit.
--
Jens Axboe
next prev parent reply other threads:[~2020-10-13 14:54 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-13 8:43 [PATCH 0/5] fixes for REQ_F_COMP_LOCKED Pavel Begunkov
2020-10-13 8:43 ` [PATCH 1/5] io_uring: don't set COMP_LOCKED if won't put Pavel Begunkov
2020-10-13 8:43 ` [PATCH 2/5] io_uring: don't unnecessarily clear F_LINK_TIMEOUT Pavel Begunkov
2020-10-13 8:43 ` [PATCH 3/5] io_uring: don't put a poll req under spinlock Pavel Begunkov
2020-10-13 14:54 ` Jens Axboe [this message]
2020-10-13 8:43 ` [PATCH 4/5] io_uring: dig out COMP_LOCK from deep call chain Pavel Begunkov
2020-10-13 8:44 ` [PATCH 5/5] io_uring: fix REQ_F_COMP_LOCKED by killing it Pavel Begunkov
2020-10-13 9:46 ` [PATCH 0/5] fixes for REQ_F_COMP_LOCKED Pavel Begunkov
2020-10-13 14:57 ` Jens Axboe
2020-10-13 17:02 ` Pavel Begunkov
2020-10-13 15:14 ` Jens Axboe
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