path: root/kernel
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authorDipankar Sarma <dipankar@in.ibm.com>2006-03-07 21:55:35 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-03-08 14:14:01 -0800
commit529bf6be5c04f2e869d07bfdb122e9fd98ade714 (patch)
tree38514bb3941c4ac2a79266e4483663b79efa2f22 /kernel
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 <dipankar@in.ibm.com> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel')
1 files changed, 4 insertions, 1 deletions
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index de2d9109194e..32b48e8ee36e 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -50,6 +50,9 @@
#include <asm/uaccess.h>
#include <asm/processor.h>
+extern int proc_nr_files(ctl_table *table, int write, struct file *filp,
+ void __user *buffer, size_t *lenp, loff_t *ppos);
#if defined(CONFIG_SYSCTL)
/* External variables not in a header file. */
@@ -943,7 +946,7 @@ static ctl_table fs_table[] = {
.data = &files_stat,
.maxlen = 3*sizeof(int),
.mode = 0444,
- .proc_handler = &proc_dointvec,
+ .proc_handler = &proc_nr_files,
.ctl_name = FS_MAXFILE,