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authorMing Lei <ming.lei@redhat.com>2022-01-10 15:29:45 +0800
committerJens Axboe <axboe@kernel.dk>2022-02-08 06:54:50 -0700
commit3301bc53358a0eb0a0db65fd7a513cd4cb50c83a (patch)
tree3f5eb173048d91b9bba51bf1457028ca2620fb60 /lib
parentabfc426d1b2fb2176df59851a64223b58ddae7e7 (diff)
lib/sbitmap: kill 'depth' from sbitmap_word
Only the last sbitmap_word can have different depth, and all the others must have same depth of 1U << sb->shift, so not necessary to store it in sbitmap_word, and it can be retrieved easily and efficiently by adding one internal helper of __map_depth(sb, index). Remove 'depth' field from sbitmap_word, then the annotation of ____cacheline_aligned_in_smp for 'word' isn't needed any more. Not see performance effect when running high parallel IOPS test on null_blk. This way saves us one cacheline(usually 64 words) per each sbitmap_word. Cc: Martin Wilck <martin.wilck@suse.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Martin Wilck <mwilck@suse.com> Reviewed-by: John Garry <john.garry@huawei.com> Link: https://lore.kernel.org/r/20220110072945.347535-1-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'lib')
-rw-r--r--lib/sbitmap.c34
1 files changed, 14 insertions, 20 deletions
diff --git a/lib/sbitmap.c b/lib/sbitmap.c
index 09d293c30fd2..b7cb96ae4701 100644
--- a/lib/sbitmap.c
+++ b/lib/sbitmap.c
@@ -85,7 +85,6 @@ int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift,
bool alloc_hint)
{
unsigned int bits_per_word;
- unsigned int i;
if (shift < 0)
shift = sbitmap_calculate_shift(depth);
@@ -117,10 +116,6 @@ int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift,
return -ENOMEM;
}
- for (i = 0; i < sb->map_nr; i++) {
- sb->map[i].depth = min(depth, bits_per_word);
- depth -= sb->map[i].depth;
- }
return 0;
}
EXPORT_SYMBOL_GPL(sbitmap_init_node);
@@ -135,11 +130,6 @@ void sbitmap_resize(struct sbitmap *sb, unsigned int depth)
sb->depth = depth;
sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word);
-
- for (i = 0; i < sb->map_nr; i++) {
- sb->map[i].depth = min(depth, bits_per_word);
- depth -= sb->map[i].depth;
- }
}
EXPORT_SYMBOL_GPL(sbitmap_resize);
@@ -184,8 +174,8 @@ static int sbitmap_find_bit_in_index(struct sbitmap *sb, int index,
int nr;
do {
- nr = __sbitmap_get_word(&map->word, map->depth, alloc_hint,
- !sb->round_robin);
+ nr = __sbitmap_get_word(&map->word, __map_depth(sb, index),
+ alloc_hint, !sb->round_robin);
if (nr != -1)
break;
if (!sbitmap_deferred_clear(map))
@@ -257,7 +247,9 @@ static int __sbitmap_get_shallow(struct sbitmap *sb,
for (i = 0; i < sb->map_nr; i++) {
again:
nr = __sbitmap_get_word(&sb->map[index].word,
- min(sb->map[index].depth, shallow_depth),
+ min_t(unsigned int,
+ __map_depth(sb, index),
+ shallow_depth),
SB_NR_TO_BIT(sb, alloc_hint), true);
if (nr != -1) {
nr += index << sb->shift;
@@ -315,11 +307,12 @@ static unsigned int __sbitmap_weight(const struct sbitmap *sb, bool set)
for (i = 0; i < sb->map_nr; i++) {
const struct sbitmap_word *word = &sb->map[i];
+ unsigned int word_depth = __map_depth(sb, i);
if (set)
- weight += bitmap_weight(&word->word, word->depth);
+ weight += bitmap_weight(&word->word, word_depth);
else
- weight += bitmap_weight(&word->cleared, word->depth);
+ weight += bitmap_weight(&word->cleared, word_depth);
}
return weight;
}
@@ -367,7 +360,7 @@ void sbitmap_bitmap_show(struct sbitmap *sb, struct seq_file *m)
for (i = 0; i < sb->map_nr; i++) {
unsigned long word = READ_ONCE(sb->map[i].word);
unsigned long cleared = READ_ONCE(sb->map[i].cleared);
- unsigned int word_bits = READ_ONCE(sb->map[i].depth);
+ unsigned int word_bits = __map_depth(sb, i);
word &= ~cleared;
@@ -531,15 +524,16 @@ unsigned long __sbitmap_queue_get_batch(struct sbitmap_queue *sbq, int nr_tags,
for (i = 0; i < sb->map_nr; i++) {
struct sbitmap_word *map = &sb->map[index];
unsigned long get_mask;
+ unsigned int map_depth = __map_depth(sb, index);
sbitmap_deferred_clear(map);
- if (map->word == (1UL << (map->depth - 1)) - 1)
+ if (map->word == (1UL << (map_depth - 1)) - 1)
continue;
- nr = find_first_zero_bit(&map->word, map->depth);
- if (nr + nr_tags <= map->depth) {
+ nr = find_first_zero_bit(&map->word, map_depth);
+ if (nr + nr_tags <= map_depth) {
atomic_long_t *ptr = (atomic_long_t *) &map->word;
- int map_tags = min_t(int, nr_tags, map->depth);
+ int map_tags = min_t(int, nr_tags, map_depth);
unsigned long val, ret;
get_mask = ((1UL << map_tags) - 1) << nr;