Re: [PATCH 1/2] mm: page allocator: Adjust the per-cpu counterthreshold when memory is low

From: David Rientjes
Date: Thu Dec 23 2010 - 18:07:18 EST


On Thu, 23 Dec 2010, Andrew Morton wrote:

> > We had to pull aa454840 "mm: page allocator: calculate a better estimate
> > of NR_FREE_PAGES when memory is low and kswapd is awake" from 2.6.36
> > internally because tests showed that it would cause the machine to stall
> > as the result of heavy kswapd activity. I merged it back with this fix as
> > it is pending in the -mm tree and it solves the issue we were seeing, so I
> > definitely think this should be pushed to -stable (and I would seriously
> > consider it for 2.6.37 inclusion even at this late date).
>
> How's about I send
> mm-page-allocator-adjust-the-per-cpu-counter-threshold-when-memory-is-low.patch
> in for 2.6.38 and tag it for backporting into 2.6.37.1 and 2.6.36.x?
> That way it'll get a bit of 2.6.38-rc testing before being merged into
> 2.6.37.x.
>

I don't think anyone would be able to answer that judgment call other than
you or Linus, it's a trade-off on whether 2.6.37 should be released with
the knowledge that it regresses just like 2.6.36 does (rendering both
unusable on some of our machines out of the box) because we're late in the
cycle.

I personally think the testing is already sufficient since it's been
sitting in -mm for two months, it's been suggested as stable material by a
couple different parties, it was a prerequisite for the transparent
hugepage series, and we've tested and merged it as fixing the regression
in 2.6.36 (as Fedora has, as far as I know). We've already merged the fix
internally, though, so it's not for selfish reasons :)
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