Commit 08cd3657 authored by Andi Kleen's avatar Andi Kleen Committed by Linus Torvalds
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[PATCH] x86_64: Optimize bitmap_weight for small bitmaps 



Use inline code bitmaps <= BITS_PER_LONG in bitmap_weight. This
gives _much_ better code.

Signed-off-by: default avatarAndi Kleen <ak@suse.de>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 5282aab8

include/linux/bitmap.h

+5 −0
Original line number Diff line number Diff line
@@ -24,6 +24,9 @@ 
 * The available bitmap operations and their rough meaning in the

 * case that the bitmap is a single unsigned long are thus:

 *

 * Note that nbits should be always a compile time evaluable constant.

 * Otherwise many inlines will generate horrible code.

 *

 * bitmap_zero(dst, nbits)			*dst = 0UL

 * bitmap_fill(dst, nbits)			*dst = ~0UL

 * bitmap_copy(dst, src, nbits)			*dst = *src
@@ -244,6 +247,8 @@ static inline int bitmap_full(const unsigned long *src, int nbits) 


static inline int bitmap_weight(const unsigned long *src, int nbits)

{

	if (nbits <= BITS_PER_LONG)

		return hweight_long(*src & BITMAP_LAST_WORD_MASK(nbits));

	return __bitmap_weight(src, nbits);

}