Messages in this thread Patch in this message | | | From | Sebastien Buisson <> | Subject | [PATCH] Increase the buffer-head per-CPU LRU size | Date | Fri, 3 Oct 2014 14:28:10 +0200 |
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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 <liang.zhen@intel.com> Signed-off-by: Andreas Dilger <andreas.dilger@intel.com> Signed-off-by: Sebastien Buisson <sebastien.buisson@bull.net> --- 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
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