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From: Jens Axboe <>
To: "Ananiev, Leonid I" <>
Subject: Re: Cfq  first request patch changes IO performance
Date: Tue, 27 Feb 2007 21:39:54 +0100	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <B41635854730A14CA71C92B36EC22AAC872B21@mssmsx411>

On Mon, Feb 26 2007, Ananiev, Leonid I wrote:
> The patch "cfq-iosched: defer slice activation to first request being
> active"
> ommitdiff;h=44f7c16065c83060cbb9dd9b367141682a6e2b8e;hp=99f9628aba4d8fb3
> b8d955c9efded0d0a1995fad
> Sysbench fileio (random read/write mix)	-15%
> Tiobench sequential write		-3%
> Tiobench random write 			-5%
> Iozone record re-write			-21%
> Iozone mmap sequential read 		-20%
> Iozone mmap random write		+45%
> Aio-stress direct sequential read		+29%
> For other 3 tiobench, 7 aiostress and 13 iozone tests the result changes
> are less than variation.
> Considered patch does not impact on performance if all threads have
> equal IO activity (tiobench).
> If single thread has IO activity the performance becomes unstable and is
> decreased mainly.

Yep there are a few unfortunate side effects, I have later fixed those.
I just need to split that patchset up and commit it.

Jens Axboe

      reply	other threads:[~2007-02-27 20:40 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-26 13:08 Cfq first request patch changes IO performance Ananiev, Leonid I
2007-02-27 20:39 ` Jens Axboe [this message]

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