Re: [patch 1/14] mm: opt rmqueue

[Nick Piggin]

Andi Kleen wrote:
> Nick Piggin <nickpiggin@xxxxxxxxxxxx> writes:
>
>
> > 1/14
> >
> > --
> > SUSE Labs, Novell Inc.
> >
> > Slightly optimise some page allocation and freeing functions by
> > taking advantage of knowing whether or not interrupts are disabled.
>
>
> Another thing that could optimize that would be to use local_t
> for the per zone statistics and the VM statistics (i have an
> old patch for the later, needs polishing up for the current
> kernel) 
> With an architecture optimized for it (like i386/x86-64) they
> generate much better code.

Yes, all this turning on and off of interrupts does have a
significant cost here.

With the full patchset applied, most of the hot path statistics
get put under areas that already require interrupts to be off,
however there are still a few I didn't get around to doing.
zone_statistics on CONFIG_NUMA, for example.

I wonder if local_t is still good on architectures like ppc64
where it still requires an ll/sc sequence?

Nick

--
SUSE Labs, Novell Inc.

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