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

Wu Fengguang
2009-04-06T22:15:09Z

On Tue, Apr 07, 2009 at 03:05:38AM +0800, 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-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> Date : 2009-02-27 9:13 (39 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
> http://lkml.org/lkml/2009/3/14/265
> Handled-By : Wu Fengguang <fengguang.wu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
>

This bug could be closed.

The performance regression is triggered by commit 1cf6e7d83bf3(mm:
task dirty accounting fix). Which has been reverted in 2.6.29.

For 2.6.30, commit 1cf6e7d83bf33(mm: task dirty accounting fix) and
1b5e62b42b55(writeback: double the dirty thresholds) were just merged
together. The latter one restores the iozone performance. (However
might deteriorate some writeback slowness bugs..)

Thanks,
Fengguang