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SubjectRe: page fault scalability patch V12 [0/7]: Overview and performance tests
Christoph Lameter wrote:
> Changes from V11->V12 of this patch:
> - dump sloppy_rss in favor of list_rss (Linus' proposal)
> - keep up against current Linus tree (patch is based on 2.6.10-rc2-bk14)


> For more than 8 cpus the page fault rate increases by orders
> of magnitude. For more than 64 cpus the improvement in performace
> is 10 times better.

Those numbers are pretty impressive. I thought you'd said with earlier
patches that performance was about doubled from 8 to 512 CPUS. Did I
remember correctly? If so, where is the improvement coming from? The
per-thread RSS I guess?

On another note, these patches are basically only helpful to new
anonymous page faults. I guess this is the main thing you are concerned
about at the moment, but I wonder if you would see improvements with
my patch to remove the ptl from the other types of faults as well?

The downside of my patch - well the main downsides - compared to yours
are its intrusiveness, and the extra cost involved in copy_page_range
which yours appears not to require.

As I've said earlier though, I wouldn't mind your patches going in. At
least they should probably get into -mm soon, when Andrew has time (and
after the 4level patches are sorted out). That wouldn't stop my patch
(possibly) being merged some time after that if and when it was found

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