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Commit d7fbd893 authored by Ajeet Yadav's avatar Ajeet Yadav Committed by Phillip Lougher
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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: default avatarAjeet Yadav <ajeet.yadav.77@gmail.com>
Signed-off-by: default avatarPhillip Lougher <phillip@squashfs.org.uk>
parent 89cab5b5

fs/squashfs/cache.c

+8 −3
Original line number Diff line number Diff line
@@ -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;

fs/squashfs/squashfs_fs_sb.h

+1 −0
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ 
struct squashfs_cache {

	char			*name;

	int			entries;

	int			curr_blk;

	int			next_blk;

	int			num_waiters;

	int			unused;