The patch titled
Subject: lib/bitmap.c: micro-optimization for __bitmap_complement()
has been added to the -mm tree. Its filename is
lib-micro-optimization-for-__bitmap_complement.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/lib-micro-optimization-for-__bitmap_complement.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/lib-micro-optimization-for-__bitmap_complement.patch
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------------------------------------------------------
From: Yury Norov <ynorov@xxxxxxxxxxxxxxxxxx>
Subject: lib/bitmap.c: micro-optimization for __bitmap_complement()
Use BITS_TO_LONGS() macro to avoid calculation of reminder (bits %
BITS_PER_LONG) On ARM64 it saves 5 instruction for function - 16 before
and 11 after.
Link: http://lkml.kernel.org/r/20180411145914.6011-1-ynorov@xxxxxxxxxxxxxxxxxx
Signed-off-by: Yury Norov <ynorov@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
Cc: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/bitmap.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff -puN lib/bitmap.c~lib-micro-optimization-for-__bitmap_complement lib/bitmap.c
--- a/lib/bitmap.c~lib-micro-optimization-for-__bitmap_complement
+++ a/lib/bitmap.c
@@ -64,12 +64,9 @@ EXPORT_SYMBOL(__bitmap_equal);
void __bitmap_complement(unsigned long *dst, const unsigned long *src, unsigned int bits)
{
- unsigned int k, lim = bits/BITS_PER_LONG;
+ unsigned int k, lim = BITS_TO_LONGS(bits);
for (k = 0; k < lim; ++k)
dst[k] = ~src[k];
-
- if (bits % BITS_PER_LONG)
- dst[k] = ~src[k];
}
EXPORT_SYMBOL(__bitmap_complement);
_
Patches currently in -mm which might be from ynorov@xxxxxxxxxxxxxxxxxx are
lib-micro-optimization-for-__bitmap_complement.patch
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