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Message-ID: <20070227203954.GI3733@kernel.dk> Date: Tue, 27 Feb 2007 21:39:54 +0100 From: Jens Axboe <jens.axboe@...cle.com> To: "Ananiev, Leonid I" <leonid.i.ananiev@...el.com> Cc: linux-kernel@...r.kernel.org Subject: Re: Cfq first request patch changes IO performance On Mon, Feb 26 2007, Ananiev, Leonid I wrote: > The patch "cfq-iosched: defer slice activation to first request being > active" > http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=c > 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 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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