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From: Jens Axboe <axboe@kernel.dk>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Sagi Grimberg <sagi@grimberg.me>
Cc: Christoph Hellwig <hch@infradead.org>,
	linux-block@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
	David Runge <dave@sleepmap.de>,
	linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org,
	Peter Zijlstra <peterz@infradead.org>,
	Daniel Wagner <dwagner@suse.de>, Mike Galbraith <efault@gmx.de>
Subject: Re: [PATCH 3/3] blk-mq: Use llist_head for blk_cpu_done
Date: Sat, 31 Oct 2020 09:01:45 -0600	[thread overview]
Message-ID: <76005875-1cfd-fb35-07f4-d35877d58b90@kernel.dk> (raw)
In-Reply-To: <3bbfb5e1-c5d7-8f3b-4b96-6dc02be0550d@kernel.dk>

On 10/31/20 9:00 AM, Jens Axboe wrote:
> On 10/31/20 4:41 AM, Sebastian Andrzej Siewior wrote:
>> On 2020-10-29 14:07:59 [-0700], Sagi Grimberg wrote:
>>>> in which context?
>>>
>>> Not sure what is the question.
>>
>> The question is in which context do you complete your requests. My guess
>> by now is "usually softirq/NAPI and context in rare error case".
> 
> There really aren't any rules for this, and it's perfectly legit to
> complete from process context. Maybe you're a kthread driven driver and
> that's how you handle completions. The block completion path has always
> been hard IRQ safe, but possible to call from anywhere.

A more recent example is polled IO, which will always complete from
process/task context and very much is fast path.

-- 
Jens Axboe


  reply	other threads:[~2020-10-31 15:01 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20201021175059.GA4989@hmbx>
2020-10-23 11:04 ` [PATCH RFC] blk-mq: Don't IPI requests on PREEMPT_RT Sebastian Andrzej Siewior
2020-10-23 11:21   ` Christoph Hellwig
2020-10-23 13:52     ` Sebastian Andrzej Siewior
2020-10-27  9:26       ` Christoph Hellwig
2020-10-27 10:11         ` Sebastian Andrzej Siewior
2020-10-27 16:07           ` Christoph Hellwig
2020-10-27 17:05             ` Thomas Gleixner
2020-10-27 17:23               ` Christoph Hellwig
2020-10-27 17:59                 ` Sebastian Andrzej Siewior
2020-10-27 20:58                 ` Sebastian Andrzej Siewior
2020-10-28  6:56                   ` Christoph Hellwig
2020-10-28 14:12                     ` [PATCH 1/3] blk-mq: Don't complete on a remote CPU in force threaded mode Sebastian Andrzej Siewior
2020-10-28 14:12                       ` [PATCH 2/3] blk-mq: Always complete remote completions requests in softirq Sebastian Andrzej Siewior
2020-10-28 14:12                       ` [PATCH 3/3] blk-mq: Use llist_head for blk_cpu_done Sebastian Andrzej Siewior
2020-10-28 14:44                         ` Christoph Hellwig
2020-10-28 14:47                           ` Sebastian Andrzej Siewior
2020-10-29 13:12                         ` Sebastian Andrzej Siewior
2020-10-29 14:05                           ` Christoph Hellwig
2020-10-29 14:56                             ` Sebastian Andrzej Siewior
2020-10-29 14:57                               ` Christoph Hellwig
2020-10-29 20:03                                 ` Sagi Grimberg
2020-10-29 21:01                                   ` Sebastian Andrzej Siewior
2020-10-29 21:07                                     ` Sagi Grimberg
2020-10-31 10:41                                       ` Sebastian Andrzej Siewior
2020-10-31 15:00                                         ` Jens Axboe
2020-10-31 15:01                                           ` Jens Axboe [this message]
2020-10-31 18:09                                             ` Christoph Hellwig
2020-11-02  9:55                                           ` Sebastian Andrzej Siewior
2020-11-02 18:12                                             ` Christoph Hellwig
2020-11-04 19:15                                               ` Sagi Grimberg
2020-11-06 15:23                                               ` Sebastian Andrzej Siewior
2020-10-28 10:04                 ` [PATCH RFC] blk-mq: Don't IPI requests on PREEMPT_RT Peter Zijlstra
2020-12-04 19:13 [PATCH 0/3 v2] blk-mq: Don't complete in IRQ, use llist_head Sebastian Andrzej Siewior
2020-12-04 19:13 ` [PATCH 3/3] blk-mq: Use llist_head for blk_cpu_done Sebastian Andrzej Siewior
2020-12-08 13:20   ` Christoph Hellwig
2020-12-08 13:28     ` Christoph Hellwig
2020-12-14 20:20     ` Sebastian Andrzej Siewior
2021-01-23 20:10 [PATCH v3 0/3] blk-mq: Don't complete in IRQ, use llist_head Sebastian Andrzej Siewior
2021-01-23 20:10 ` [PATCH 3/3] blk-mq: Use llist_head for blk_cpu_done Sebastian Andrzej Siewior
2021-01-25  8:30   ` Christoph Hellwig
2021-01-25  8:32     ` Sebastian Andrzej Siewior
2021-01-25  8:39       ` Christoph Hellwig

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