Re: [BUG] Commit d065bd81 severely regresses huge page allocationsuccess rates

[Michel Lespinasse]

On Thu, Nov 11, 2010 at 4:15 AM, Mel Gorman <mel@xxxxxxxxx> wrote:
> When testing 2.6.37-rc1, I noticed that huge page allocation success
> rates were severely impaired. Bisection showed that commit [d065bd81: mm:
> retry page fault when blocking on disk transfer] was the biggest factor.
> Reverting the patch confirmed this. Here are the results of a high-order
> allocation stress test. The vanilla kernel is 2.6.37-rc1 and the revert
> kernel has this commit removed with minor conflicts cleaned up.
[...]
> I have not digested what the patch is doing but am reporting it in case
> people familiar with the patch spot the problem quickly.

There was a bug in that commit, which was fixed in
d88c0922fa0e2c021a028b310a641126c6d4b7dc

I think this may explain the issue; compaction won't work well if
extra references are kept :/

Can you check that this indeed solves your test case ?

-- 
Michel "Walken" Lespinasse
A program is never fully debugged until the last user dies.
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