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SubjectRe: hackbench regression since 2.6.25-rc
On Fri, 14 Mar 2008, Zhang, Yanmin wrote:

> > Ahhh... Okay those slabs did not change for 2.6.25-rc. Is there
> > really a difference to 2.6.24?
> As oprofile shows slub functions spend more than 80% cpu time, I would like
> to focus on optimizing SLUB before going back to 2.6.24.

I thought you wanted to address a regression vs 2.6.24?

> kmalloc-512: No NUMA information available.
>
> Slab Perf Counter Alloc Free %Al %Fr
> --------------------------------------------------
> Fastpath 55039159 5006829 68 6
> Slowpath 24975754 75007769 31 93
> Page Alloc 73840 73779 0 0
> Add partial 0 24341085 0 30
> Remove partial 24267297 73779 30 0

^^^ add partial/remove partial is likely the cause for
trouble here. 30% is unacceptably high. The larger allocs will reduce the
partial handling overhead. That is likely the effect that we see here.

> Refill 24975738

Duh refills at 50%? We could try to just switch to another slab instead of
reusing the existing one. May also affect the add/remove partial
situation.





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