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From: Ingo Molnar <mingo@kernel.org>
To: Jens Axboe <axboe@kernel.dk>
Cc: "Pavel Begunkov (Silence)" <asml.silence@gmail.com>,
	Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 0/2] Optimise io_uring completion waiting
Date: Mon, 23 Sep 2019 10:35:49 +0200	[thread overview]
Message-ID: <20190923083549.GA42487@gmail.com> (raw)
In-Reply-To: <a4996ae7-ac0a-447b-49b2-7e96275aad29@kernel.dk>


* Jens Axboe <axboe@kernel.dk> wrote:

> On 9/22/19 2:08 AM, Pavel Begunkov (Silence) wrote:
> > From: Pavel Begunkov <asml.silence@gmail.com>
> > 
> > There could be a lot of overhead within generic wait_event_*() used for
> > waiting for large number of completions. The patchset removes much of
> > it by using custom wait event (wait_threshold).
> > 
> > Synthetic test showed ~40% performance boost. (see patch 2)
> 
> I'm fine with the io_uring side of things, but to queue this up we
> really need Peter or Ingo to sign off on the core wakeup bits...
> 
> Peter?

I'm not sure an extension is needed for such a special interface, why not 
just put a ->threshold value next to the ctx->wait field and use either 
the regular wait_event() APIs with the proper condition, or 
wait_event_cmd() style APIs if you absolutely need something more complex 
to happen inside?

Should result in a much lower linecount and no scheduler changes. :-)

Thanks,

	Ingo

  reply	other threads:[~2019-09-23  8:35 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-22  8:08 [PATCH v2 0/2] Optimise io_uring completion waiting Pavel Begunkov (Silence)
2019-09-22  8:08 ` [PATCH v2 1/2] sched/wait: Add wait_threshold Pavel Begunkov (Silence)
2019-09-23  7:19   ` Peter Zijlstra
2019-09-23 16:37     ` Pavel Begunkov
2019-09-23 19:27       ` Peter Zijlstra
2019-09-23 20:23         ` Peter Zijlstra
2019-09-24  6:44         ` Pavel Begunkov
2019-09-22  8:08 ` [PATCH v2 2/2] io_uring: Optimise cq waiting with wait_threshold Pavel Begunkov (Silence)
2019-09-22 15:51 ` [PATCH v2 0/2] Optimise io_uring completion waiting Jens Axboe
2019-09-23  8:35   ` Ingo Molnar [this message]
2019-09-23 16:21     ` Pavel Begunkov
2019-09-23 16:32       ` Pavel Begunkov
2019-09-23 20:48         ` Jens Axboe
2019-09-23 23:00           ` Jens Axboe
2019-09-24  7:06             ` Pavel Begunkov
2019-09-24  8:02               ` Jens Axboe
2019-09-24  8:27                 ` Jens Axboe
2019-09-24  8:36                   ` Jens Axboe
2019-09-24  9:33                     ` Pavel Begunkov
2019-09-24 10:11                       ` Jens Axboe
2019-09-24  9:49                     ` Peter Zijlstra
2019-09-24 10:13                       ` Jens Axboe
2019-09-24 10:34                         ` Jens Axboe
2019-09-24 11:11                           ` Pavel Begunkov
2019-09-24 11:15                             ` Jens Axboe
2019-09-24 11:23                               ` Pavel Begunkov
2019-09-24 13:13                                 ` Jens Axboe
2019-09-24 17:33                                   ` Pavel Begunkov
2019-09-24 17:46                                     ` Jens Axboe
2019-09-24 18:28                                       ` Pavel Begunkov
2019-09-24 19:32                                         ` Jens Axboe
2019-09-24 11:43                             ` Peter Zijlstra
2019-09-24 12:57                               ` Jens Axboe
2019-09-24 11:33                           ` Peter Zijlstra
2019-09-24  9:20                   ` Pavel Begunkov
2019-09-24 10:09                     ` Jens Axboe
2019-09-24  9:21                 ` Pavel Begunkov
2019-09-24 10:09                   ` Jens Axboe

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