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

Linus Torvalds
2009-03-15T00:31:46Z

On Sat, 14 Mar 2009, Rafael J. Wysocki wrote:
>
> 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 (16 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>

I suspect that I should just raise the default dirty limits. Wu reported
that it fixed the regression, and while he picked some rather high
percentages, I think we could certainly raise the rather aggressive
default ones.

After all, those default percentages were picked (a) with the old dirty
logic and (b) largely at random and (c) designed to be aggressive. In
particular, that (a) means that having fixed some of the dirty accounting,
maybe the real bug is now that it was always too aggressive, just hidden
by an accounting issue.

If we raised the default ratio from 5/10 to 10/20, what happens to the
iozone regression?

Linus