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

[Wu Fengguang]

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@xxxxxxxxx>
> 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@xxxxxxxxx>
> 

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

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