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

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Message-ID: <da86ec56-5f14-536d-2d43-2cc9e118d2a7@kernel.dk>
Date:   Tue, 24 Sep 2019 13:15:52 +0200
From:   Jens Axboe <axboe@...nel.dk>
To:     Pavel Begunkov <asml.silence@...il.com>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     Ingo Molnar <mingo@...nel.org>, Ingo Molnar <mingo@...hat.com>,
        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 5:11 AM, Pavel Begunkov wrote:
> On 24/09/2019 13:34, Jens Axboe wrote:
>> On 9/24/19 4:13 AM, Jens Axboe wrote:
>>> On 9/24/19 3:49 AM, Peter Zijlstra wrote:
>>>> On Tue, Sep 24, 2019 at 10:36:28AM +0200, Jens Axboe wrote:
>>>>
>>>>> +struct io_wait_queue {
>>>>> +	struct wait_queue_entry wq;
>>>>> +	struct io_ring_ctx *ctx;
>>>>> +	struct task_struct *task;
>>>>
>>>> wq.private is where the normal waitqueue stores the task pointer.
>>>>
>>>> (I'm going to rename that)
>>>
>>> If you do that, then we can just base the io_uring parts on that.
>>
>> Just took a quick look at it, and ran into block/kyber-iosched.c that
>> actually uses the private pointer for something that isn't a task
>> struct...
>>
> 
> Let reuse autoremove_wake_function anyway. Changed a bit your patch:

Yep that should do it, and saves 8 bytes of stack as well.

BTW, did you test my patch, this one or the previous? Just curious if it
worked for you.

-- 
Jens Axboe