Messages in this thread | | | Subject | Re: iozone write 50% regression in kernel 2.6.24-rc1 | From | "Zhang, Yanmin" <> | Date | Mon, 12 Nov 2007 08:45:57 +0800 |
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On Fri, 2007-11-09 at 04:36 -0800, Martin Knoblauch wrote: > ----- Original Message ---- > > From: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com> > > To: a.p.zijlstra@chello.nl > > Cc: LKML <linux-kernel@vger.kernel.org> > > Sent: Friday, November 9, 2007 10:47:52 AM > > Subject: iozone write 50% regression in kernel 2.6.24-rc1 > > > > Comparing with 2.6.23, iozone sequential write/rewrite (512M) has > > 50% > > > regression > > in kernel 2.6.24-rc1. 2.6.24-rc2 has the same regression. > > > > My machine has 8 processor cores and 8GB memory. > > > > By bisect, I located patch > > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h= > > 04fbfdc14e5f48463820d6b9807daa5e9c92c51f. > > > > > > Another behavior: with kernel 2.6.23, if I run iozone for many > > times > > > after rebooting machine, > > the result looks stable. But with 2.6.24-rc1, the first run of > > iozone > > > got a very small result and > > following run has 4Xorig_result. > > > > What I reported is the regression of 2nd/3rd run, because first run > > has > > > bigger regression. > > > > I also tried to change > > /proc/sys/vm/dirty_ratio,dirty_backgroud_ratio > > > and didn't get improvement. > could you tell us the exact iozone command you are using? iozone -i 0 -r 4k -s 512m
> I would like to repeat it on my setup, because I definitely see the opposite behaviour in 2.6.24-rc1/rc2. The speed there is much better than in 2.6.22 and before (I skipped 2.6.23, because I was waiting for the per-bdi changes). I definitely do not see the difference between 1st and subsequent runs. But then, I do my tests with 5GB file sizes like: > > iozone3_283/src/current/iozone -t 5 -F /scratch/X1 /scratch/X2 /scratch/X3 /scratch/X4 /scratch/X5 -s 5000M -r 1024 -c -e -i 0 -i 1 My machine uses SATA (AHCI) disk.
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