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); _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
