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| author | Yury Norov <yury.norov@gmail.com> | 2022-09-17 20:07:12 -0700 |
|---|---|---|
| committer | Yury Norov <yury.norov@gmail.com> | 2022-09-26 12:19:12 -0700 |
| commit | 24291caf8447f6fc060c8d00136bdc30ee207f38 (patch) | |
| tree | 13d0a9d2b34cc58777852bce8ed9732c3882e669 /include/linux/bitmap.h | |
| parent | 70a1cb106d9410f1f37e0261728e46722b74c29f (diff) | |
| download | linux-24291caf8447f6fc060c8d00136bdc30ee207f38.tar.gz | |
lib/bitmap: add bitmap_weight_and()
The function calculates Hamming weight of (bitmap1 & bitmap2). Now we
have to do like this:
tmp = bitmap_alloc(nbits);
bitmap_and(tmp, map1, map2, nbits);
weight = bitmap_weight(tmp, nbits);
bitmap_free(tmp);
This requires additional memory, adds pressure on alloc subsystem, and
way less cache-friendly than just:
weight = bitmap_weight_and(map1, map2, nbits);
The following patches apply it for cpumask functions.
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Diffstat (limited to 'include/linux/bitmap.h')
| -rw-r--r-- | include/linux/bitmap.h | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h index f65410a49fda..b2aef45af0db 100644 --- a/include/linux/bitmap.h +++ b/include/linux/bitmap.h @@ -51,6 +51,7 @@ struct device; * bitmap_empty(src, nbits) Are all bits zero in *src? * bitmap_full(src, nbits) Are all bits set in *src? * bitmap_weight(src, nbits) Hamming Weight: number set bits + * bitmap_weight_and(src1, src2, nbits) Hamming Weight of and'ed bitmap * bitmap_set(dst, pos, nbits) Set specified bit area * bitmap_clear(dst, pos, nbits) Clear specified bit area * bitmap_find_next_zero_area(buf, len, pos, n, mask) Find bit free area @@ -164,6 +165,8 @@ bool __bitmap_intersects(const unsigned long *bitmap1, bool __bitmap_subset(const unsigned long *bitmap1, const unsigned long *bitmap2, unsigned int nbits); unsigned int __bitmap_weight(const unsigned long *bitmap, unsigned int nbits); +unsigned int __bitmap_weight_and(const unsigned long *bitmap1, + const unsigned long *bitmap2, unsigned int nbits); void __bitmap_set(unsigned long *map, unsigned int start, int len); void __bitmap_clear(unsigned long *map, unsigned int start, int len); @@ -439,6 +442,15 @@ unsigned int bitmap_weight(const unsigned long *src, unsigned int nbits) return __bitmap_weight(src, nbits); } +static __always_inline +unsigned long bitmap_weight_and(const unsigned long *src1, + const unsigned long *src2, unsigned int nbits) +{ + if (small_const_nbits(nbits)) + return hweight_long(*src1 & *src2 & BITMAP_LAST_WORD_MASK(nbits)); + return __bitmap_weight_and(src1, src2, nbits); +} + static __always_inline void bitmap_set(unsigned long *map, unsigned int start, unsigned int nbits) { |