On Fri, 24 Jun 2005 12:33, [email protected] wrote: > --- Con Kolivas <[email protected]> wrote: > > I found the same, and the effect was blunted by noatime and > > journal_data_writeback (on ext3). Try them one at a time and see what you > > get. > > I had to move to a different box, but get the same kind of results (for > ext3 default mount options). > > Here are the latencies (all cfq) I get with different values for the mount > parameters > > ext2 default > 0.1s > > ext3 default > 52.6s avg > > reiser defaults > 29s avg 5 minutes > then, > 12.9s avg > > ext3 rw,noatime,data=writeback > 0.1s avg > > reiser rw,noatime,data=writeback > 4s avg for 20 seconds > then 0.1 seconds avg > > > So, indeed adding noatime,data=writeback to the mount options improves > things a lot. > I also tried without the noatime, and that doesn't make much difference to > me. > > That looks like a good workaround, I'll now try with the actual server and > see how things go. That's more or less what I found, although I found noatime also helped my test cases, but also less than the journal options. Coincidentally I only discovered this recently and hadn't gotten around to telling anyone how dramatic this was and this seemed as good a time as any. I am suspicious that it wasn't this bad in past kernels but haven't been able to instrument earlier kernels to check. Cheers, Con
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