diff options
| author | Jan Kara <jack@suse.cz> | 2016-02-22 18:23:47 -0500 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2016-02-22 18:23:47 -0500 |
| commit | f0c8b46238db9d51ef9ea0858259958d0c601cec (patch) | |
| tree | 67a5822eb2c25bf5c89e6e52a81e6fc8cde7d7ba /include | |
| parent | c2f3140fe2eceb3a6c1615b2648b9471544881c6 (diff) | |
mbcache2: Use referenced bit instead of LRU
Currently we maintain perfect LRU list by moving entry to the tail of
the list when it gets used. However these operations on cache-global
list are relatively expensive.
In this patch we switch to lazy updates of LRU list. Whenever entry gets
used, we set a referenced bit in it. When reclaiming entries, we give
referenced entries another round in the LRU. Since the list is not a
real LRU anymore, rename it to just 'list'.
In my testing this logic gives about 30% boost to workloads with mostly
unique xattr blocks (e.g. xattr-bench with 10 files and 10000 unique
xattr values).
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/mbcache2.h | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/include/linux/mbcache2.h b/include/linux/mbcache2.h index b6f160ff2533..c934843a6a31 100644 --- a/include/linux/mbcache2.h +++ b/include/linux/mbcache2.h @@ -10,8 +10,8 @@ struct mb2_cache; struct mb2_cache_entry { - /* LRU list - protected by cache->c_lru_list_lock */ - struct list_head e_lru_list; + /* List of entries in cache - protected by cache->c_list_lock */ + struct list_head e_list; /* Hash table list - protected by bitlock in e_hash_list_head */ struct hlist_bl_node e_hash_list; atomic_t e_refcnt; @@ -19,8 +19,11 @@ struct mb2_cache_entry { u32 e_key; /* Block number of hashed block - stable during lifetime of the entry */ sector_t e_block; - /* Head of hash list (for list bit lock) - stable */ - struct hlist_bl_head *e_hash_list_head; + /* + * Head of hash list (for list bit lock) - stable. Combined with + * referenced bit of entry + */ + unsigned long _e_hash_list_head; }; struct mb2_cache *mb2_cache_create(int bucket_bits); |