path: root/fs/dcache.c
diff options
authorDipankar Sarma <>2006-03-07 21:55:35 -0800
committerLinus Torvalds <>2006-03-08 14:14:01 -0800
commit529bf6be5c04f2e869d07bfdb122e9fd98ade714 (patch)
tree38514bb3941c4ac2a79266e4483663b79efa2f22 /fs/dcache.c
parent21a1ea9eb40411d4ee29448c53b9e4c0654d6ceb (diff)
[PATCH] fix file counting
I have benchmarked this on an x86_64 NUMA system and see no significant performance difference on kernbench. Tested on both x86_64 and powerpc. The way we do file struct accounting is not very suitable for batched freeing. For scalability reasons, file accounting was constructor/destructor based. This meant that nr_files was decremented only when the object was removed from the slab cache. This is susceptible to slab fragmentation. With RCU based file structure, consequent batched freeing and a test program like Serge's, we just speed this up and end up with a very fragmented slab - llm22:~ # cat /proc/sys/fs/file-nr 587730 0 758844 At the same time, I see only a 2000+ objects in filp cache. The following patch I fixes this problem. This patch changes the file counting by removing the filp_count_lock. Instead we use a separate percpu counter, nr_files, for now and all accesses to it are through get_nr_files() api. In the sysctl handler for nr_files, we populate files_stat.nr_files before returning to user. Counting files as an when they are created and destroyed (as opposed to inside slab) allows us to correctly count open files with RCU. Signed-off-by: Dipankar Sarma <> Cc: "Paul E. McKenney" <> Cc: "David S. Miller" <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'fs/dcache.c')
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/dcache.c b/fs/dcache.c
index a173bba32666..11dc83092d4a 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1736,7 +1736,7 @@ void __init vfs_caches_init(unsigned long mempages)
filp_cachep = kmem_cache_create("filp", sizeof(struct file), 0,
- SLAB_HWCACHE_ALIGN|SLAB_PANIC, filp_ctor, filp_dtor);