Re: [PATCH 8/8] Add VM counters for transparent hugepages

Andrea Arcangeli
2011-02-22T16:45:03Z

On Tue, Feb 22, 2011 at 08:36:26AM -0800, Dave Hansen wrote:
> On Mon, 2011-02-21 at 11:07 -0800, Andi Kleen wrote:
> > From: Andi Kleen <ak@linux.intel.com>
> >
> > I found it difficult to make sense of transparent huge pages without
> > having any counters for its actions. Add some counters to vmstat
> > for allocation of transparent hugepages and fallback to smaller
> > pages.
> >
> > Optional patch, but useful for development and understanding the system.
>
> Very nice. I did the same thing, splits-only. I also found this stuff
> a must-have for trying to do any work with transparent hugepages. It's
> just impossible otherwise.

This patch is good too. 1 and 8 I think can go in, patch 1 is high
priority.

Patches 2-5 I've an hard time to see how they're not hurting
performance instead of improving it, especially patch 3 looks dead
wrong and has no chance by the very design of KSM and by the random
(vma-ignoring) NUMA affinity of PageKSM, patch 3 is most certainly a
regression.

Patch 6-7 I didn't evaluate those yet, they look good, even if low
priority.

Acked-by: Andrea Arcangeli <aarcange@redhat.com>