Messages in this thread | | | Date | Fri, 9 Nov 2007 04:36:14 -0800 (PST) | From | Martin Knoblauch <> | Subject | Re: iozone write 50% regression in kernel 2.6.24-rc1 |
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----- 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. > > -yanmin > - Hi Yanmin,
could you tell us the exact iozone command you are using? 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
Kind regards Martin
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