The patch titled
Avoid divides in BITS_TO_LONGS
has been added to the -mm tree. Its filename is
avoid-divides-in-bits_to_longs.patch
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------------------------------------------------------
Subject: Avoid divides in BITS_TO_LONGS
From: Eric Dumazet <[EMAIL PROTECTED]>
BITS_PER_LONG is a signed value (32 or 64)
DIV_ROUND_UP(nr, BITS_PER_LONG) performs signed arithmetic if "nr" is signed
too.
Converting BITS_TO_LONGS(nr) to DIV_ROUND_UP(nr, BITS_PER_BYTE *
sizeof(long)) makes sure compiler can perform a right shift, even if "nr"
is a signed value, instead of an expensive integer divide.
Applying this patch saves 141 bytes on x86 when CONFIG_CC_OPTIMIZE_FOR_SIZE=y
and speedup bitmap operations.
Signed-off-by: Eric Dumazet <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
---
include/linux/bitops.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN include/linux/bitops.h~avoid-divides-in-bits_to_longs
include/linux/bitops.h
--- a/include/linux/bitops.h~avoid-divides-in-bits_to_longs
+++ a/include/linux/bitops.h
@@ -6,8 +6,8 @@
#define BIT(nr) (1UL << (nr))
#define BIT_MASK(nr) (1UL << ((nr) % BITS_PER_LONG))
#define BIT_WORD(nr) ((nr) / BITS_PER_LONG)
-#define BITS_TO_LONGS(nr) DIV_ROUND_UP(nr, BITS_PER_LONG)
#define BITS_PER_BYTE 8
+#define BITS_TO_LONGS(nr) DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long))
#endif
/*
_
Patches currently in -mm which might be from [EMAIL PROTECTED] are
origin.patch
avoid-divides-in-bits_to_longs.patch
-
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