Commit 86cf78d7 authored by Sebastien Buisson's avatar Sebastien Buisson Committed by Linus Torvalds

fs/buffer.c: increase the buffer-head per-CPU LRU size

Increase the buffer-head per-CPU LRU size to allow efficient filesystem
operations that access many blocks for each transaction.  For example,
creating a file in a large ext4 directory with quota enabled will access
multiple buffer heads and will overflow the LRU at the default 8-block LRU
size:

* parent directory inode table block (ctime, nlinks for subdirs)
* new inode bitmap
* inode table block
* 2 quota blocks
* directory leaf block (not reused, but pollutes one cache entry)
* 2 levels htree blocks (only one is reused, other pollutes cache)
* 2 levels indirect/index blocks (only one is reused)

The buffer-head per-CPU LRU size is raised to 16, as it shows in metadata
performance benchmarks up to 10% gain for create, 4% for lookup and 7% for
destroy.
Signed-off-by: default avatarLiang Zhen <liang.zhen@intel.com>
Signed-off-by: default avatarAndreas Dilger <andreas.dilger@intel.com>
Signed-off-by: default avatarSebastien Buisson <sebastien.buisson@bull.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2c0346a3
......@@ -1253,7 +1253,7 @@ static struct buffer_head *__bread_slow(struct buffer_head *bh)
* a local interrupt disable for that.
*/
#define BH_LRU_SIZE 8
#define BH_LRU_SIZE 16
struct bh_lru {
struct buffer_head *bhs[BH_LRU_SIZE];
......
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