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Message-ID: <1652181274-136198-2-git-send-email-john.garry@huawei.com>
Date: Tue, 10 May 2022 19:14:33 +0800
From: John Garry <john.garry@...wei.com>
To: <axboe@...nel.dk>, <linux-block@...r.kernel.org>
CC: <linux-kernel@...r.kernel.org>, <linux-scsi@...r.kernel.org>,
John Garry <john.garry@...wei.com>
Subject: [RFC PATCH 1/2] sbitmap: Make sbitmap.map a double pointer
Currently sbitmap.map points to a single array of sbitmap words.
To allow each word to be allocated individually, make it a double pointer.
This will mean that to access to a word will require an extra load.
Signed-off-by: John Garry <john.garry@...wei.com>
---
include/linux/sbitmap.h | 11 ++++++-----
lib/sbitmap.c | 34 ++++++++++++++++++++++++----------
2 files changed, 30 insertions(+), 15 deletions(-)
diff --git a/include/linux/sbitmap.h b/include/linux/sbitmap.h
index 8f5a86e210b9..46268f391e32 100644
--- a/include/linux/sbitmap.h
+++ b/include/linux/sbitmap.h
@@ -68,7 +68,7 @@ struct sbitmap {
/**
* @map: Allocated bitmap.
*/
- struct sbitmap_word *map;
+ struct sbitmap_word **map;
/*
* @alloc_hint: Cache of last successfully allocated or freed bit.
@@ -256,9 +256,10 @@ static inline void __sbitmap_for_each_set(struct sbitmap *sb,
unsigned int depth = min_t(unsigned int,
__map_depth(sb, index) - nr,
sb->depth - scanned);
-
+ struct sbitmap_word *map = sb->map[index];
scanned += depth;
- word = sb->map[index].word & ~sb->map[index].cleared;
+
+ word = map->word & ~map->cleared;
if (!word)
goto next;
@@ -299,7 +300,7 @@ static inline void sbitmap_for_each_set(struct sbitmap *sb, sb_for_each_fn fn,
static inline unsigned long *__sbitmap_word(struct sbitmap *sb,
unsigned int bitnr)
{
- return &sb->map[SB_NR_TO_INDEX(sb, bitnr)].word;
+ return &sb->map[SB_NR_TO_INDEX(sb, bitnr)]->word;
}
/* Helpers equivalent to the operations in asm/bitops.h and linux/bitmap.h */
@@ -322,7 +323,7 @@ static inline void sbitmap_clear_bit(struct sbitmap *sb, unsigned int bitnr)
*/
static inline void sbitmap_deferred_clear_bit(struct sbitmap *sb, unsigned int bitnr)
{
- unsigned long *addr = &sb->map[SB_NR_TO_INDEX(sb, bitnr)].cleared;
+ unsigned long *addr = &sb->map[SB_NR_TO_INDEX(sb, bitnr)]->cleared;
set_bit(SB_NR_TO_BIT(sb, bitnr), addr);
}
diff --git a/lib/sbitmap.c b/lib/sbitmap.c
index ae4fd4de9ebe..64fb9800ed8c 100644
--- a/lib/sbitmap.c
+++ b/lib/sbitmap.c
@@ -85,6 +85,8 @@ int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift,
bool alloc_hint)
{
unsigned int bits_per_word;
+ struct sbitmap_word *map;
+ int index;
if (shift < 0)
shift = sbitmap_calculate_shift(depth);
@@ -116,6 +118,17 @@ int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift,
return -ENOMEM;
}
+ map = kvzalloc_node(sb->map_nr * sizeof(**sb->map), flags, node);
+ if (!map)
+ return -ENOMEM;
+
+ for (index = 0; index < sb->map_nr; index++, map++) {
+ struct sbitmap_word **_map;
+
+ _map = &sb->map[index];
+ *_map = map;
+ }
+
return 0;
}
EXPORT_SYMBOL_GPL(sbitmap_init_node);
@@ -126,7 +139,7 @@ void sbitmap_resize(struct sbitmap *sb, unsigned int depth)
unsigned int i;
for (i = 0; i < sb->map_nr; i++)
- sbitmap_deferred_clear(&sb->map[i]);
+ sbitmap_deferred_clear(sb->map[i]);
sb->depth = depth;
sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word);
@@ -170,7 +183,7 @@ static int __sbitmap_get_word(unsigned long *word, unsigned long depth,
static int sbitmap_find_bit_in_index(struct sbitmap *sb, int index,
unsigned int alloc_hint)
{
- struct sbitmap_word *map = &sb->map[index];
+ struct sbitmap_word *map = sb->map[index];
int nr;
do {
@@ -246,7 +259,7 @@ 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,
+ nr = __sbitmap_get_word(&sb->map[index]->word,
min_t(unsigned int,
__map_depth(sb, index),
shallow_depth),
@@ -256,7 +269,7 @@ static int __sbitmap_get_shallow(struct sbitmap *sb,
break;
}
- if (sbitmap_deferred_clear(&sb->map[index]))
+ if (sbitmap_deferred_clear(sb->map[index]))
goto again;
/* Jump to next index. */
@@ -294,7 +307,7 @@ bool sbitmap_any_bit_set(const struct sbitmap *sb)
unsigned int i;
for (i = 0; i < sb->map_nr; i++) {
- if (sb->map[i].word & ~sb->map[i].cleared)
+ if (sb->map[i]->word & ~sb->map[i]->cleared)
return true;
}
return false;
@@ -306,7 +319,7 @@ static unsigned int __sbitmap_weight(const struct sbitmap *sb, bool set)
unsigned int i, weight = 0;
for (i = 0; i < sb->map_nr; i++) {
- const struct sbitmap_word *word = &sb->map[i];
+ const struct sbitmap_word *word = sb->map[i];
unsigned int word_depth = __map_depth(sb, i);
if (set)
@@ -358,8 +371,9 @@ void sbitmap_bitmap_show(struct sbitmap *sb, struct seq_file *m)
int i;
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);
+ struct sbitmap_word *map = READ_ONCE(sb->map[i]);
+ unsigned long word = READ_ONCE(map->word);
+ unsigned long cleared = READ_ONCE(map->cleared);
unsigned int word_bits = __map_depth(sb, i);
word &= ~cleared;
@@ -522,7 +536,7 @@ unsigned long __sbitmap_queue_get_batch(struct sbitmap_queue *sbq, int nr_tags,
index = SB_NR_TO_INDEX(sb, hint);
for (i = 0; i < sb->map_nr; i++) {
- struct sbitmap_word *map = &sb->map[index];
+ struct sbitmap_word *map = sb->map[index];
unsigned long get_mask;
unsigned int map_depth = __map_depth(sb, index);
@@ -665,7 +679,7 @@ void sbitmap_queue_clear_batch(struct sbitmap_queue *sbq, int offset,
unsigned long *this_addr;
/* since we're clearing a batch, skip the deferred map */
- this_addr = &sb->map[SB_NR_TO_INDEX(sb, tag)].word;
+ this_addr = &sb->map[SB_NR_TO_INDEX(sb, tag)]->word;
if (!addr) {
addr = this_addr;
} else if (addr != this_addr) {
--
2.26.2
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