linux-kernel - Re: [PATCH v2 0/2] Optimise io

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Message-ID: <65a1f01e-e8f5-0da8-eb3c-48c5749c9568@kernel.dk>
Date:   Tue, 24 Sep 2019 12:09:31 +0200
From:   Jens Axboe <axboe@...nel.dk>
To:     Pavel Begunkov <asml.silence@...il.com>,
        Ingo Molnar <mingo@...nel.org>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/2] Optimise io_uring completion waiting

On 9/24/19 3:21 AM, Pavel Begunkov wrote:
> On 24/09/2019 11:02, Jens Axboe wrote:
>> On 9/24/19 1:06 AM, Pavel Begunkov wrote:
>>> On 24/09/2019 02:00, Jens Axboe wrote:
>>>>> I think we can do the same thing, just wrapping the waitqueue in a
>>>>> structure with a count in it, on the stack. Got some flight time
>>>>> coming up later today, let me try and cook up a patch.
>>>>
>>>> Totally untested, and sent out 5 min before departure... But something
>>>> like this.
>>> Hmm, reminds me my first version. Basically that's the same thing but
>>> with macroses inlined. I wanted to make it reusable and self-contained,
>>> though.
>>>
>>> If you don't think it could be useful in other places, sure, we could do
>>> something like that. Is that so?
>>
>> I totally agree it could be useful in other places. Maybe formalized and
>> used with wake_up_nr() instead of adding a new primitive? Haven't looked
>> into that, I may be talking nonsense.
> 
> @nr there is about number of tasks to wake up. AFAIK doesn't solve the
> problem.

Ah right, embarassingly I'm actually the one that added that
functionality ages ago...

-- 
Jens Axboe