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From: Jens Axboe <[email protected]>
To: [email protected], [email protected],
	Andres Freund <[email protected]>
Cc: Pavel Begunkov <[email protected]>
Subject: Re: [PATCH v1] io_uring: Use io_schedule* in cqring wait
Date: Fri, 07 Jul 2023 11:53:55 -0600	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>


On Fri, 07 Jul 2023 09:20:07 -0700, Andres Freund wrote:
> I observed poor performance of io_uring compared to synchronous IO. That
> turns out to be caused by deeper CPU idle states entered with io_uring,
> due to io_uring using plain schedule(), whereas synchronous IO uses
> io_schedule().
> 
> The losses due to this are substantial. On my cascade lake workstation,
> t/io_uring from the fio repository e.g. yields regressions between 20%
> and 40% with the following command:
> ./t/io_uring -r 5 -X0 -d 1 -s 1 -c 1 -p 0 -S$use_sync -R 0 /mnt/t2/fio/write.0.0
> 
> [...]

Applied, thanks!

[1/1] io_uring: Use io_schedule* in cqring wait
      (no commit info)

Best regards,
-- 
Jens Axboe




      parent reply	other threads:[~2023-07-07 17:53 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-07 16:20 [PATCH v1] io_uring: Use io_schedule* in cqring wait Andres Freund
2023-07-07 17:11 ` Jens Axboe
2023-07-07 17:53 ` Jens Axboe [this message]

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