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[PATCH] Fix up per-cpu page batch sizes

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The code to clamp batch sizes to 2^n - 1 went missing and an extra
check got added, which must have been a hunk of the "higer order pcp
batch refills" work sneaking in.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Nick Piggin 2005-12-04 13:55:25 +11:00 committed by Linus Torvalds
parent 9a40525788
commit 0ceaacc978
1 changed files with 8 additions and 8 deletions
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16
mm/page_alloc.c
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@ -1772,16 +1772,16 @@ static int __devinit zone_batchsize(struct zone *zone)
batch = 1;
/*
* We will be trying to allcoate bigger chunks of contiguous
* memory of the order of fls(batch). This should result in
* better cache coloring.
* Clamp the batch to a 2^n - 1 value. Having a power
* of 2 value was found to be more likely to have
* suboptimal cache aliasing properties in some cases.
*
* A sanity check also to ensure that batch is still in limits.
* For example if 2 tasks are alternately allocating
* batches of pages, one task can end up with a lot
* of pages of one half of the possible page colors
* and the other with pages of the other colors.
*/
batch = (1 << fls(batch + batch/2));
if (fls(batch) >= (PAGE_SHIFT + MAX_ORDER - 2))
batch = PAGE_SHIFT + ((MAX_ORDER - 1 - PAGE_SHIFT)/2);
batch = (1 << (fls(batch + batch/2)-1)) - 1;
return batch;
}