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[PATCH] mm: micro optimise zone_watermark_ok
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Having min be a signed quantity means gcc can't turn high latency divides
into shifts.  There happen to be two such divides for GFP_ATOMIC (ie.
networking, ie.  important) allocations, one of which depends on the other.
 Fixing this makes code smaller as a bonus.

Shame on somebody (probably me).

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Nick Piggin authored and Linus Torvalds committed Oct 4, 2006
1 parent b2abacf commit e80ee88
Showing 1 changed file with 2 additions and 1 deletion.
3 changes: 2 additions & 1 deletion mm/page_alloc.c
Original file line number Diff line number Diff line change
Expand Up @@ -900,7 +900,8 @@ int zone_watermark_ok(struct zone *z, int order, unsigned long mark,
int classzone_idx, int alloc_flags)
{
/* free_pages my go negative - that's OK */
long min = mark, free_pages = z->free_pages - (1 << order) + 1;
unsigned long min = mark;
long free_pages = z->free_pages - (1 << order) + 1;
int o;

if (alloc_flags & ALLOC_HIGH)
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