From: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx> Subject: bitmap: optimise bitmap_set and bitmap_clear of a single bit We have eight users calling bitmap_clear for a single bit and seventeen calling bitmap_set for a single bit. Rather than fix all of them to call __clear_bit or __set_bit, turn bitmap_clear and bitmap_set into inline functions and make this special case efficient. Link: http://lkml.kernel.org/r/20170628153221.11322-3-willy@xxxxxxxxxxxxx Signed-off-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx> Acked-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx> Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/bitmap.h | 23 ++++++++++++++++++++--- lib/bitmap.c | 8 ++++---- lib/test_bitmap.c | 3 --- 3 files changed, 24 insertions(+), 10 deletions(-) diff -puN include/linux/bitmap.h~bitmap-optimise-bitmap_set-and-bitmap_clear-of-a-single-bit include/linux/bitmap.h --- a/include/linux/bitmap.h~bitmap-optimise-bitmap_set-and-bitmap_clear-of-a-single-bit +++ a/include/linux/bitmap.h @@ -112,9 +112,8 @@ extern int __bitmap_intersects(const uns extern int __bitmap_subset(const unsigned long *bitmap1, const unsigned long *bitmap2, unsigned int nbits); extern int __bitmap_weight(const unsigned long *bitmap, unsigned int nbits); - -extern void bitmap_set(unsigned long *map, unsigned int start, int len); -extern void bitmap_clear(unsigned long *map, unsigned int start, int len); +extern void __bitmap_set(unsigned long *map, unsigned int start, int len); +extern void __bitmap_clear(unsigned long *map, unsigned int start, int len); extern unsigned long bitmap_find_next_zero_area_off(unsigned long *map, unsigned long size, @@ -315,6 +314,24 @@ static __always_inline int bitmap_weight return __bitmap_weight(src, nbits); } +static __always_inline void bitmap_set(unsigned long *map, unsigned int start, + unsigned int nbits) +{ + if (__builtin_constant_p(nbits) && nbits == 1) + __set_bit(start, map); + else + __bitmap_set(map, start, nbits); +} + +static __always_inline void bitmap_clear(unsigned long *map, unsigned int start, + unsigned int nbits) +{ + if (__builtin_constant_p(nbits) && nbits == 1) + __clear_bit(start, map); + else + __bitmap_clear(map, start, nbits); +} + static inline void bitmap_shift_right(unsigned long *dst, const unsigned long *src, unsigned int shift, int nbits) { diff -puN lib/bitmap.c~bitmap-optimise-bitmap_set-and-bitmap_clear-of-a-single-bit lib/bitmap.c --- a/lib/bitmap.c~bitmap-optimise-bitmap_set-and-bitmap_clear-of-a-single-bit +++ a/lib/bitmap.c @@ -251,7 +251,7 @@ int __bitmap_weight(const unsigned long } EXPORT_SYMBOL(__bitmap_weight); -void bitmap_set(unsigned long *map, unsigned int start, int len) +void __bitmap_set(unsigned long *map, unsigned int start, int len) { unsigned long *p = map + BIT_WORD(start); const unsigned int size = start + len; @@ -270,9 +270,9 @@ void bitmap_set(unsigned long *map, unsi *p |= mask_to_set; } } -EXPORT_SYMBOL(bitmap_set); +EXPORT_SYMBOL(__bitmap_set); -void bitmap_clear(unsigned long *map, unsigned int start, int len) +void __bitmap_clear(unsigned long *map, unsigned int start, int len) { unsigned long *p = map + BIT_WORD(start); const unsigned int size = start + len; @@ -291,7 +291,7 @@ void bitmap_clear(unsigned long *map, un *p &= ~mask_to_clear; } } -EXPORT_SYMBOL(bitmap_clear); +EXPORT_SYMBOL(__bitmap_clear); /** * bitmap_find_next_zero_area_off - find a contiguous aligned zero area diff -puN lib/test_bitmap.c~bitmap-optimise-bitmap_set-and-bitmap_clear-of-a-single-bit lib/test_bitmap.c --- a/lib/test_bitmap.c~bitmap-optimise-bitmap_set-and-bitmap_clear-of-a-single-bit +++ a/lib/test_bitmap.c @@ -333,9 +333,6 @@ static void __init test_bitmap_u32_array } } -#define __bitmap_set(a, b, c) bitmap_set(a, b, c) -#define __bitmap_clear(a, b, c) bitmap_clear(a, b, c) - static void noinline __init test_mem_optimisations(void) { DECLARE_BITMAP(bmap1, 1024); _ -- 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
