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: Liang Zhen Signed-off-by: Andreas Dilger Signed-off-by: Sebastien Buisson --- fs/buffer.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/fs/buffer.c b/fs/buffer.c index 6024877..a6468f2 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -1256,7 +1256,7 @@ 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]; -- 1.7.1