Re: [Bug #12809] iozone regression with 2.6.29-rc6

Rafael J. Wysocki
2009-03-07T21:36:37Z

On Thursday 05 March 2009, Wu Fengguang wrote:
> On Tue, Mar 03, 2009 at 09:25:59PM +0200, Rafael J. Wysocki wrote:
> > This message has been generated automatically as a part of a report
> > of recent regressions.
> >
> > The following bug entry is on the current list of known regressions
> > from 2.6.28. Please verify if it still should be listed and let me know
> > (either way).
> >
> >
> > Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=12809
> > Subject : iozone regression with 2.6.29-rc6
> > Submitter : Lin Ming <ming.m.lin@intel.com>
> > Date : 2009-02-27 9:13 (5 days old)
> > First-Bad-Commit: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=1cf6e7d83bf334cc5916137862c920a97aabc018
> > References : http://marc.info/?l=linux-kernel&m=123572630504360&w=4
> > Handled-By : Wu Fengguang <fengguang.wu@intel.com>
>
> Following Peter's idea of relaxing writeback throttling, Lin Ming
> and I tried the idea of totally disabling writeback throttling by
> doing benchmarks with the following parameters:
>
> echo 60 > /proc/sys/vm/dirty_ratio
> echo 50 > /proc/sys/vm/dirty_background_ratio
>
> The result is encouraging: the iozone performance is restored to the
> level of 2.6.29-rc5!
>
> We'll continue to evaluate the dirty/throttling numbers with Nick's patch.

Thanks for the update.

Rafael