Re: [PATCH v2] KSM: numa awareness sysfs knob

From: David Rientjes
Date: Fri Jun 29 2012 - 18:30:26 EST


On Fri, 29 Jun 2012, Johannes Weiner wrote:

> > I started with exactly same idea as you described above in the first
> > RFC, link: https://lkml.org/lkml/2011/11/30/91
> > But this approach turned out to be more complicated than it looked
> > (see two last emails in thread) and complexity of solution would rise
> > a lot.
>
> Oh, I should have checked the archives given that it's v2. I expected
> it to get complex but didn't put enough thought into it to see /that/
> amount of complexity. Sorry.
>
> Carry on, then :-)
>

I don't think it's an unfair amount of complexity to ask for, and I don't
see the problem with ksm merging two pages that have a distance under the
configured threshold and leaving the third page unmerged; by configuring
the threshold (which should be a char, not an int) the admin has specified
the locality that is necessary for optimal performance so has knowingly
restricted ksm in that way.

I'd rename it to ksm_merge_distance, which is more similar to
reclaim_distance, and return to the first version of this patch.
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