Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH v2 0/2] Optimise io_uring completion waiting
To:     Pavel Begunkov <asml.silence@gmail.com>,
        Ingo Molnar <mingo@kernel.org>
Cc:     Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
References: <cover.1569139018.git.asml.silence@gmail.com>
 <a4996ae7-ac0a-447b-49b2-7e96275aad29@kernel.dk>
 <20190923083549.GA42487@gmail.com>
 <c15b2d54-c722-8fb4-266f-b589c1a21aa5@gmail.com>
 <df612e90-8999-0085-d2d6-4418e044e429@gmail.com>
 <731b2087-7786-5374-68ff-8cba42f0cd68@kernel.dk>
 <759b9b48-1de3-1d43-3e39-9c530bfffaa0@kernel.dk>
 <43244626-9cfd-0c0b-e7a1-878363712ef3@gmail.com>
 <f2608e3d-bb4e-9984-79e8-a2ab4f855c7f@kernel.dk>
 <38ea2681-dbf0-457a-dcc0-406d10e2572b@gmail.com>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <65a1f01e-e8f5-0da8-eb3c-48c5749c9568@kernel.dk>
Date:   Tue, 24 Sep 2019 12:09:31 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101
 Thunderbird/60.8.0
MIME-Version: 1.0
In-Reply-To: <38ea2681-dbf0-457a-dcc0-406d10e2572b@gmail.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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