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From: Jens Axboe <[email protected]>
To: Pavel Begunkov <[email protected]>,
	[email protected], [email protected]
Subject: Re: [PATCH 0/2] task_put batching
Date: Sat, 18 Jul 2020 08:37:04 -0600	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

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


  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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