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authorAndi Kleen <ak@suse.de>2006-06-26 13:57:10 +0200
committerLinus Torvalds <torvalds@g5.osdl.org>2006-06-26 10:48:16 -0700
commit08cd36570e47176c7b6bd3e80125aa46c4638097 (patch)
tree02c9cb3be4a2b520772e9b66bb57901401dd2666
parent5282aab87a8be3f5e6c36a4c2ee4b71852def1bb (diff)
[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: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--include/linux/bitmap.h5
1 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index d9ed2796985..dcc5de7cc48 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -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);
}