On Mon, 2007-11-12 at 04:58 -0800, Martin Knoblauch wrote: > ----- Original Message ---- > > From: "Zhang, Yanmin" <[EMAIL PROTECTED]> > > To: Martin Knoblauch <[EMAIL PROTECTED]> > > Cc: [EMAIL PROTECTED]; LKML <linux-kernel@vger.kernel.org> > > Sent: Monday, November 12, 2007 1:45:57 AM > > Subject: Re: iozone write 50% regression in kernel 2.6.24-rc1 > > > > On Fri, 2007-11-09 at 04:36 -0800, Martin Knoblauch wrote: > > > ----- Original Message ---- > > > > From: "Zhang, Yanmin" > > > > To: [EMAIL PROTECTED] > > > > Cc: LKML > > > > 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 > > > > OK, I definitely do not see the reported effect. On a HP Proliant with a > RAID5 on CCISS I get: > > 2.6.19.2: 654-738 MB/sec write, 1126-1154 MB/sec rewrite > 2.6.24-rc2: 772-820 MB/sec write, 1495-1539 MB/sec rewrite > > The first run is always slowest, all subsequent runs are faster and the same > speed. Although the first run is always slowest, but if we compare 2.6.23 and 2.6.24-rc, we could find the first run result of 2.6.23 is 7 times of the one of 2.6.24-rc.
Originally, my test suite is just to pick up the result of first run. I might change my test suite to make it run for many times. Now I run the the test manually for many times after machine reboots. Comparing 2.6.24-rc with 2.6.23, 3rd and following run of 2.6.24-rc has about 50% regression. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
