From: Jens Axboe <[email protected]>
To: Pavel Begunkov <[email protected]>, [email protected]
Subject: Re: [PATCH RFC] io_uring: remove retries from io_wq_submit_work()
Date: Mon, 24 Feb 2020 08:27:19 -0700 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <843cc96a407b2cbfe869d9665c8120bdde34683e.1582535688.git.asml.silence@gmail.com>
On 2/24/20 2:15 AM, Pavel Begunkov wrote:
> It seems no opcode may return -EAGAIN for non-blocking case and expect
> to be reissued. Remove retry code from io_wq_submit_work().
There's actually a comment right there on how that's possible :-)
Normally, for block IO, we can wait for request slots if we run out.
For polled IO, that isn't possible since the task itself is the one
that will find completions and hence free request slots as well. If
the submitting task is allowed to sleep waiting for requests that it
itself are supposed to find and complete, then we'd hang. Hence we
return -EAGAIN for that case, and have no other choice for polled
IO than to retry.
--
Jens Axboe
next prev parent reply other threads:[~2020-02-24 15:27 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-24 9:15 [PATCH RFC] io_uring: remove retries from io_wq_submit_work() Pavel Begunkov
2020-02-24 15:27 ` Jens Axboe [this message]
2020-02-24 15:40 ` Pavel Begunkov
2020-02-24 18:16 ` Jens Axboe
2020-02-24 18:33 ` Pavel Begunkov
2020-02-24 18:37 ` Jens Axboe
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