From: Pavel Begunkov <asml.silence@gmail.com>
To: Jens Axboe <axboe@kernel.dk>, io-uring@vger.kernel.org
Subject: Re: [PATCH 1/4] io_uring: Always REQ_F_FREE_SQE for allocated sqe
Date: Wed, 20 Nov 2019 12:03:30 +0300 [thread overview]
Message-ID: <4eea8a32-68dc-4d34-f69d-5a2281594844@gmail.com> (raw)
In-Reply-To: <0655d5c5-e241-034c-6ec2-ad97012fd2f1@kernel.dk>
On 11/20/2019 1:10 AM, Jens Axboe wrote:
> and it is tempting as a cleanup, but it
> also moves it into the fastpath instead of keeping it in the slow
> link fail path. Any allocated sqe is normally freed when the work
> is processed, which is generally also a better path to do it in as
> we know we're not under locks/irq disabled.
Good point with locks/irq, but io_put_req() is usually called out of
locking. Isn't it? E.g. @completion_lock is taken mainly by *add_cq_event().
SQE needs to be freed in any case, and there is only one extra "if",
what we really should not worry about. There are much heavier parts.
e.g. excessive atomics/locking, I'll send an RFC for that, if needed.
I find the complexity of much more concern here.
--
Pavel Begunkov
next prev parent reply other threads:[~2019-11-20 9:03 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-19 20:32 [PATCHSET 0/4][io_uring-post] cleanup after linked timeouts Pavel Begunkov
2019-11-19 20:32 ` [PATCH 1/4] io_uring: Always REQ_F_FREE_SQE for allocated sqe Pavel Begunkov
2019-11-19 22:10 ` Jens Axboe
2019-11-20 9:03 ` Pavel Begunkov [this message]
2019-11-20 14:25 ` Jens Axboe
2019-11-19 20:32 ` [PATCH 2/4] io_uring: break links for failed defer Pavel Begunkov
2019-11-19 20:32 ` [PATCH 3/4] io_uring: remove redundant check Pavel Begunkov
2019-11-19 20:32 ` [PATCH 4/4] io_uring: Fix leaking linked timeouts Pavel Begunkov
2019-11-19 22:10 ` [PATCHSET 0/4][io_uring-post] cleanup after " Jens Axboe
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