Re: KSWAPD Algorithm

From: Andi Kleen
Date: Wed Dec 03 2008 - 09:51:13 EST

"wassim dagash" <wassim.dagash@xxxxxxxxx> writes:

> Hi All,
> Description:
> I countered a weird problem with kswapd:
> it runs in some infinite loop trying to swap until order 10 of zone
> highmem is OK, While zone higmem (as I understand) has nothing to do
> with contiguous physical memory (cause there is no 1-1 mapping) which
> means kswapd will continue to try to balance order 10 of zone highmem
> forever (or until someone release a very large chunk of highmem).
> Can anyone please explain me the algorithm of kswapd and why it tries
> to balance order 10 of zone higmem ?

hugetlbfs requires large continuous mappings even in highmem
to map 2MB pages or similar to user space.
However order 10 seems pretty high, normally that's only order 8
on a i386 system.


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