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Subject: Re: [PATCH v3] io_uring: don't wait when under-submitting
To:     Pavel Begunkov <asml.silence@gmail.com>, io-uring@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <6256169d519f72fe592e70be47a04aa0e9c3b9a1.1576333754.git.asml.silence@gmail.com>
 <c6f625bdb27ea3b929d0717ebf2aaa33ad5410da.1576335142.git.asml.silence@gmail.com>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <a1f0a9ed-085f-dd6f-9038-62d701f4c354@kernel.dk>
Date:   Sat, 14 Dec 2019 11:43:37 -0700
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On 12/14/19 7:53 AM, Pavel Begunkov wrote:
> There is no reliable way to submit and wait in a single syscall, as
> io_submit_sqes() may under-consume sqes (in case of an early error).
> Then it will wait for not-yet-submitted requests, deadlocking the user
> in most cases.
> 
> In such cases adjust min_complete, so it won't wait for more than
> what have been submitted in the current call to io_uring_enter(). It
> may be less than totally in-flight including previous submissions,
> but this shouldn't do harm and up to a user.

Thanks, applied.

-- 
Jens Axboe