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Squashfs: optimise squashfs_cache_get entry search 

squashfs_cache_get() iterates over all entries to search for
 block its looking for. Often get() / put() are called for
 same block.

If we cache the current entry index, then we can optimise the
subsequent *_get() calls.

Signed-off-by: Ajeet Yadav <ajeet.yadav.77@gmail.com>
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
This commit is contained in:
Ajeet Yadav 2011-12-27 15:10:04 +05:30 committed by Phillip Lougher
parent 89cab5b572
commit d7fbd89338
2 changed files with 9 additions and 3 deletions
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11
fs/squashfs/cache.c
View File

@ -70,11 +70,15 @@ struct squashfs_cache_entry *squashfs_cache_get(struct super_block *sb,
spin_lock(&cache->lock);
while (1) {
for (i = 0; i < cache->entries; i++)
if (cache->entry[i].block == block)
for (i = cache->curr_blk, n = 0; n < cache->entries; n++) {
if (cache->entry[i].block == block) {
cache->curr_blk = i;
break;
}
i = (i + 1) % cache->entries;
}
if (i == cache->entries) {
if (n == cache->entries) {
/*
* Block not in cache, if all cache entries are used
* go to sleep waiting for one to become available.
@ -245,6 +249,7 @@ struct squashfs_cache *squashfs_cache_init(char *name, int entries,
goto cleanup;
}
cache->curr_blk = 0;
cache->next_blk = 0;
cache->unused = entries;
cache->entries = entries;

1
fs/squashfs/squashfs_fs_sb.h
View File

@ -28,6 +28,7 @@
struct squashfs_cache {
char *name;
int entries;
int curr_blk;
int next_blk;
int num_waiters;
int unused;