From 3301bc53358a0eb0a0db65fd7a513cd4cb50c83a Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Mon, 10 Jan 2022 15:29:45 +0800 Subject: [PATCH] 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 Signed-off-by: Ming Lei Reviewed-by: Martin Wilck Reviewed-by: John Garry Link: https://lore.kernel.org/r/20220110072945.347535-1-ming.lei@redhat.com Signed-off-by: Jens Axboe --- include/linux/sbitmap.h | 17 ++++++++++------- lib/sbitmap.c | 34 ++++++++++++++-------------------- 2 files changed, 24 insertions(+), 27 deletions(-) diff --git a/include/linux/sbitmap.h b/include/linux/sbitmap.h index 95df357ec009..df3b584b0f0c 100644 --- a/include/linux/sbitmap.h +++ b/include/linux/sbitmap.h @@ -27,15 +27,10 @@ struct seq_file; * struct sbitmap_word - Word in a &struct sbitmap. */ struct sbitmap_word { - /** - * @depth: Number of bits being used in @word/@cleared - */ - unsigned long depth; - /** * @word: word holding free bits */ - unsigned long word ____cacheline_aligned_in_smp; + unsigned long word; /** * @cleared: word holding cleared bits @@ -164,6 +159,14 @@ struct sbitmap_queue { int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift, gfp_t flags, int node, bool round_robin, bool alloc_hint); +/* sbitmap internal helper */ +static inline unsigned int __map_depth(const struct sbitmap *sb, int index) +{ + if (index == sb->map_nr - 1) + return sb->depth - (index << sb->shift); + return 1U << sb->shift; +} + /** * sbitmap_free() - Free memory used by a &struct sbitmap. * @sb: Bitmap to free. @@ -251,7 +254,7 @@ static inline void __sbitmap_for_each_set(struct sbitmap *sb, while (scanned < sb->depth) { unsigned long word; unsigned int depth = min_t(unsigned int, - sb->map[index].depth - nr, + __map_depth(sb, index) - nr, sb->depth - scanned); scanned += depth; 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;