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>
This commit is contained in:
Yury Norov 2022-09-17 20:07:12 -07:00
parent 70a1cb106d
commit 24291caf84
3 changed files with 44 additions and 9 deletions

View File

@ -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)
{

View File

@ -586,6 +586,17 @@ static inline unsigned int cpumask_weight(const struct cpumask *srcp)
return bitmap_weight(cpumask_bits(srcp), nr_cpumask_bits);
}
/**
* cpumask_weight_and - Count of bits in (*srcp1 & *srcp2)
* @srcp1: the cpumask to count bits (< nr_cpu_ids) in.
* @srcp2: the cpumask to count bits (< nr_cpu_ids) in.
*/
static inline unsigned int cpumask_weight_and(const struct cpumask *srcp1,
const struct cpumask *srcp2)
{
return bitmap_weight_and(cpumask_bits(srcp1), cpumask_bits(srcp2), nr_cpumask_bits);
}
/**
* cpumask_shift_right - *dstp = *srcp >> n
* @dstp: the cpumask result

View File

@ -333,20 +333,32 @@ bool __bitmap_subset(const unsigned long *bitmap1,
}
EXPORT_SYMBOL(__bitmap_subset);
#define BITMAP_WEIGHT(FETCH, bits) \
({ \
unsigned int __bits = (bits), idx, w = 0; \
\
for (idx = 0; idx < __bits / BITS_PER_LONG; idx++) \
w += hweight_long(FETCH); \
\
if (__bits % BITS_PER_LONG) \
w += hweight_long((FETCH) & BITMAP_LAST_WORD_MASK(__bits)); \
\
w; \
})
unsigned int __bitmap_weight(const unsigned long *bitmap, unsigned int bits)
{
unsigned int k, lim = bits/BITS_PER_LONG, w = 0;
for (k = 0; k < lim; k++)
w += hweight_long(bitmap[k]);
if (bits % BITS_PER_LONG)
w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
return w;
return BITMAP_WEIGHT(bitmap[idx], bits);
}
EXPORT_SYMBOL(__bitmap_weight);
unsigned int __bitmap_weight_and(const unsigned long *bitmap1,
const unsigned long *bitmap2, unsigned int bits)
{
return BITMAP_WEIGHT(bitmap1[idx] & bitmap2[idx], bits);
}
EXPORT_SYMBOL(__bitmap_weight_and);
void __bitmap_set(unsigned long *map, unsigned int start, int len)
{
unsigned long *p = map + BIT_WORD(start);