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DateMon, 6 Jun 2011 14:38:51 +0200
FromAndrea Arcangeli <>
SubjectRe: [PATCH] mm: compaction: Abort compaction if too many pages are isolated and caller is asynchronous
On Mon, Jun 06, 2011 at 11:39:24AM +0100, Mel Gorman wrote:
> Well spotted.
>
> Acked-by: Mel Gorman <mgorman@suse.de>
>
> Minor nit. swapper_space is rarely referred to outside of the swap
> code. Might it be more readable to use
>
> /*
> * swapcache is accounted as NR_FILE_PAGES but it is not
> * accounted as NR_SHMEM
> *
> if (PageSwapBacked(page) && !PageSwapCache(page))

I thought the comparison on swapper_space would be faster as it was
immediate vs register in CPU, instead of forcing a memory
access. Otherwise I would have used the above. Now the test_bit is
written in C and lockless so it's not likely to be very different
considering the cacheline is hot in the CPU but it's still referencing
memory instead register vs immediate comparison.


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