From: Jens Axboe <axboe@kernel.dk>
To: Pavel Begunkov <asml.silence@gmail.com>,
io-uring@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/2] task_put batching
Date: Sat, 18 Jul 2020 08:37:04 -0600 [thread overview]
Message-ID: <cf209c59-547e-0a69-244d-7c1fec00a978@kernel.dk> (raw)
In-Reply-To: <cover.1595021626.git.asml.silence@gmail.com>
On 7/18/20 2:32 AM, Pavel Begunkov wrote:
> For my a bit exaggerated test case perf continues to show high CPU
> cosumption by io_dismantle(), and so calling it io_iopoll_complete().
> Even though the patch doesn't yield throughput increase for my setup,
> probably because the effect is hidden behind polling, but it definitely
> improves relative percentage. And the difference should only grow with
> increasing number of CPUs. Another reason to have this is that atomics
> may affect other parallel tasks (e.g. which doesn't use io_uring)
>
> before:
> io_iopoll_complete: 5.29%
> io_dismantle_req: 2.16%
>
> after:
> io_iopoll_complete: 3.39%
> io_dismantle_req: 0.465%
Still not seeing a win here, but it's clean and it _should_ work. For
some reason I end up getting the offset in task ref put growing the
fput_many(). Which doesn't (on the surface) make a lot of sense, but
may just mean that we have some weird side effects.
I have applied it, thanks.
--
Jens Axboe
next prev parent reply other threads:[~2020-07-18 14:37 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-18 8:32 [PATCH 0/2] task_put batching Pavel Begunkov
2020-07-18 8:32 ` [PATCH 1/2] tasks: add put_task_struct_many() Pavel Begunkov
2020-07-18 8:32 ` [PATCH 2/2] io_uring: batch put_task_struct() Pavel Begunkov
2020-07-18 14:37 ` Jens Axboe [this message]
2020-07-19 11:15 ` [PATCH 0/2] task_put batching Pavel Begunkov
2020-07-19 18:49 ` Jens Axboe
2020-07-20 14:18 ` Pavel Begunkov
2020-07-20 15:22 ` Pavel Begunkov
2020-07-20 15:49 ` Jens Axboe
2020-07-20 16:06 ` Pavel Begunkov
2020-07-20 16:11 ` Jens Axboe
2020-07-20 16:42 ` Pavel Begunkov
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