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>
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@ -27,15 +27,10 @@ struct seq_file;
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* struct sbitmap_word - Word in a &struct sbitmap.
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*/
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struct sbitmap_word {
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/**
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* @depth: Number of bits being used in @word/@cleared
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*/
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unsigned long depth;
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/**
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* @word: word holding free bits
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*/
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unsigned long word ____cacheline_aligned_in_smp;
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unsigned long word;
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/**
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* @cleared: word holding cleared bits
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@ -164,6 +159,14 @@ struct sbitmap_queue {
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int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift,
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gfp_t flags, int node, bool round_robin, bool alloc_hint);
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/* sbitmap internal helper */
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static inline unsigned int __map_depth(const struct sbitmap *sb, int index)
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{
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if (index == sb->map_nr - 1)
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return sb->depth - (index << sb->shift);
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return 1U << sb->shift;
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}
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/**
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* sbitmap_free() - Free memory used by a &struct sbitmap.
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* @sb: Bitmap to free.
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@ -251,7 +254,7 @@ static inline void __sbitmap_for_each_set(struct sbitmap *sb,
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while (scanned < sb->depth) {
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unsigned long word;
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unsigned int depth = min_t(unsigned int,
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sb->map[index].depth - nr,
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__map_depth(sb, index) - nr,
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sb->depth - scanned);
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scanned += depth;
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@ -85,7 +85,6 @@ int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift,
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bool alloc_hint)
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{
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unsigned int bits_per_word;
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unsigned int i;
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if (shift < 0)
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shift = sbitmap_calculate_shift(depth);
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@ -117,10 +116,6 @@ int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift,
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return -ENOMEM;
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}
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for (i = 0; i < sb->map_nr; i++) {
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sb->map[i].depth = min(depth, bits_per_word);
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depth -= sb->map[i].depth;
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}
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return 0;
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}
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EXPORT_SYMBOL_GPL(sbitmap_init_node);
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@ -135,11 +130,6 @@ void sbitmap_resize(struct sbitmap *sb, unsigned int depth)
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sb->depth = depth;
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sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word);
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for (i = 0; i < sb->map_nr; i++) {
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sb->map[i].depth = min(depth, bits_per_word);
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depth -= sb->map[i].depth;
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}
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}
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EXPORT_SYMBOL_GPL(sbitmap_resize);
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@ -184,8 +174,8 @@ static int sbitmap_find_bit_in_index(struct sbitmap *sb, int index,
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int nr;
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do {
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nr = __sbitmap_get_word(&map->word, map->depth, alloc_hint,
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!sb->round_robin);
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nr = __sbitmap_get_word(&map->word, __map_depth(sb, index),
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alloc_hint, !sb->round_robin);
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if (nr != -1)
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break;
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if (!sbitmap_deferred_clear(map))
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@ -257,7 +247,9 @@ static int __sbitmap_get_shallow(struct sbitmap *sb,
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for (i = 0; i < sb->map_nr; i++) {
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again:
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nr = __sbitmap_get_word(&sb->map[index].word,
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min(sb->map[index].depth, shallow_depth),
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min_t(unsigned int,
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__map_depth(sb, index),
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shallow_depth),
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SB_NR_TO_BIT(sb, alloc_hint), true);
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if (nr != -1) {
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nr += index << sb->shift;
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@ -315,11 +307,12 @@ static unsigned int __sbitmap_weight(const struct sbitmap *sb, bool set)
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for (i = 0; i < sb->map_nr; i++) {
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const struct sbitmap_word *word = &sb->map[i];
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unsigned int word_depth = __map_depth(sb, i);
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if (set)
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weight += bitmap_weight(&word->word, word->depth);
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weight += bitmap_weight(&word->word, word_depth);
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else
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weight += bitmap_weight(&word->cleared, word->depth);
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weight += bitmap_weight(&word->cleared, word_depth);
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}
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return weight;
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}
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@ -367,7 +360,7 @@ void sbitmap_bitmap_show(struct sbitmap *sb, struct seq_file *m)
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for (i = 0; i < sb->map_nr; i++) {
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unsigned long word = READ_ONCE(sb->map[i].word);
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unsigned long cleared = READ_ONCE(sb->map[i].cleared);
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unsigned int word_bits = READ_ONCE(sb->map[i].depth);
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unsigned int word_bits = __map_depth(sb, i);
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word &= ~cleared;
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@ -531,15 +524,16 @@ unsigned long __sbitmap_queue_get_batch(struct sbitmap_queue *sbq, int nr_tags,
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for (i = 0; i < sb->map_nr; i++) {
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struct sbitmap_word *map = &sb->map[index];
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unsigned long get_mask;
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unsigned int map_depth = __map_depth(sb, index);
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sbitmap_deferred_clear(map);
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if (map->word == (1UL << (map->depth - 1)) - 1)
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if (map->word == (1UL << (map_depth - 1)) - 1)
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continue;
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nr = find_first_zero_bit(&map->word, map->depth);
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if (nr + nr_tags <= map->depth) {
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nr = find_first_zero_bit(&map->word, map_depth);
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if (nr + nr_tags <= map_depth) {
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atomic_long_t *ptr = (atomic_long_t *) &map->word;
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int map_tags = min_t(int, nr_tags, map->depth);
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int map_tags = min_t(int, nr_tags, map_depth);
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unsigned long val, ret;
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get_mask = ((1UL << map_tags) - 1) << nr;
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