From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Christoph Hellwig <hch@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Daniel Wagner <dwagner@suse.de>, Mike Galbraith <efault@gmx.de>,
Sagi Grimberg <sagi@grimberg.me>
Subject: Re: [PATCH 2/3] blk-mq: Always complete remote completions requests in softirq
Date: Thu, 17 Dec 2020 17:43:08 +0100 [thread overview]
Message-ID: <20201217164308.ueki3scv3oxt4uta@linutronix.de> (raw)
In-Reply-To: <20201208131319.GB22219@infradead.org>
On 2020-12-08 13:13:19 [+0000], Christoph Hellwig wrote:
> On Mon, Dec 07, 2020 at 04:52:57PM -0700, Jens Axboe wrote:
> > On 12/4/20 12:13 PM, Sebastian Andrzej Siewior wrote:
> > > Controllers with multiple queues have their IRQ-handelers pinned to a
> > > CPU. The core shouldn't need to complete the request on a remote CPU.
> > >
> > > Remove this case and always raise the softirq to complete the request.
> >
> > I don't like this one at all, it'll add a softirq jump for the fast path
> > for eg nvme devices.
>
> For the real fast path, that is either a polled queue or irq driven
> queues that only map to a single CPU we are never reaching this code,
> so I'm not too worried. Not that I'd complain about numbers, preferably
> in the commit log.
Did Daniel provide all the numbers you/Jens were looking for or do we
still wait for some?
Sebastian
next prev parent reply other threads:[~2020-12-17 16:43 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
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 1/3] blk-mq: Don't complete on a remote CPU in force threaded mode Sebastian Andrzej Siewior
2020-12-08 13:10 ` Christoph Hellwig
2020-12-04 19:13 ` [PATCH 2/3] blk-mq: Always complete remote completions requests in softirq Sebastian Andrzej Siewior
2020-12-07 23:52 ` Jens Axboe
2020-12-08 8:22 ` Sebastian Andrzej Siewior
2020-12-08 8:44 ` Daniel Wagner
2020-12-08 11:36 ` Daniel Wagner
2020-12-08 11:49 ` Sebastian Andrzej Siewior
2020-12-08 12:41 ` Daniel Wagner
2020-12-08 12:52 ` Sebastian Andrzej Siewior
2020-12-08 12:57 ` Sebastian Andrzej Siewior
2020-12-08 13:27 ` Daniel Wagner
2020-12-17 16:45 ` Jens Axboe
2020-12-17 16:49 ` Daniel Wagner
2020-12-17 16:54 ` Jens Axboe
2020-12-08 13:13 ` Christoph Hellwig
2020-12-17 16:43 ` Sebastian Andrzej Siewior [this message]
2020-12-17 16:55 ` Jens Axboe
2020-12-17 16:58 ` Sebastian Andrzej Siewior
2020-12-17 17:05 ` Daniel Wagner
2020-12-17 18:16 ` Daniel Wagner
2020-12-17 18:22 ` Jens Axboe
2020-12-17 18:41 ` Daniel Wagner
2020-12-17 18:46 ` Jens Axboe
2020-12-17 19:07 ` Daniel Wagner
2020-12-17 19:13 ` Jens Axboe
2020-12-17 19:15 ` Daniel Wagner
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
-- strict thread matches above, loose matches on Subject: below --
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 2/3] blk-mq: Always complete remote completions requests in softirq Sebastian Andrzej Siewior
2021-01-25 7:10 ` Hannes Reinecke
2021-01-25 8:25 ` Christoph Hellwig
2021-01-25 8:30 ` Sebastian Andrzej Siewior
2021-01-25 8:32 ` Christoph Hellwig
2021-01-25 9:29 ` Sebastian Andrzej Siewior
2021-01-25 8:22 ` Christoph Hellwig
2021-01-25 8:49 ` Christoph Hellwig
2021-01-27 11:22 ` Daniel Wagner
2020-10-28 6:56 [PATCH RFC] blk-mq: Don't IPI requests on PREEMPT_RT 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
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