linux-kernel - Re: [PATCHSET v4] blk-mq-scheduling framework

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Message-ID: <d75c44df-8eac-b324-ac11-9bb7b6190603@fb.com>
Date:   Mon, 23 Jan 2017 10:42:16 -0700
From:   Jens Axboe <axboe@...com>
To:     Paolo Valente <paolo.valente@...aro.org>
CC:     Jens Axboe <axboe@...nel.dk>, <linux-block@...r.kernel.org>,
        Linux-Kernal <linux-kernel@...r.kernel.org>,
        Omar Sandoval <osandov@...com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Mark Brown <broonie@...nel.org>
Subject: Re: [PATCHSET v4] blk-mq-scheduling framework

On 01/23/2017 10:04 AM, Paolo Valente wrote:
> 
>> Il giorno 18 gen 2017, alle ore 17:21, Jens Axboe <axboe@...com> ha scritto:
>>
>> On 01/18/2017 08:14 AM, Paolo Valente wrote:
>>> according to the function blk_mq_sched_put_request, the
>>> mq.completed_request hook seems to always be invoked (if set) for a
>>> request for which the mq.put_rq_priv is invoked (if set).
>>
>> Correct, any request that came out of blk_mq_sched_get_request()
>> will always have completed called on it, regardless of whether it
>> had IO started on it or not.
>>
> 
> It seems that some request, after being dispatched, happens to have no
> mq.put_rq_priv invoked on it now or then.  Is it expected?  If it is,
> could you point me to the path through which the end of the life of
> such a request is handled?

I'm guessing that's a flush request. I added RQF_QUEUED to check for
that, if RQF_QUEUED is set, you know it has come from your get_request
handler.

I'm assuming that is it, let me know.

-- 
Jens Axboe