cgroups: use a hash table for css_set finding
authorLi Zefan <lizf@cn.fujitsu.com>
Tue, 29 Apr 2008 08:00:11 +0000 (01:00 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Tue, 29 Apr 2008 15:06:09 +0000 (08:06 -0700)
commit472b1053f3c319cc60bfb2a0bb062fed77a93eb6
tree2ef88bfdb7e397d3718a1bed38f13194f894097e
parent08ce5f16ee466ffc5bf243800deeecd77d9eaf50
cgroups: use a hash table for css_set finding

When we attach a process to a different cgroup, the css_set linked-list will
be run through to find a suitable existing css_set to use.  This patch
implements a hash table for better performance.

The following benchmarks have been tested:

For N in 1, 5, 10, 50, 100, 500, 1000, create N cgroups with one sleeping
task in each, and then move an additional task through each cgroup in
turn.

Here is a test result:

N Loop orig - Time(s) hash - Time(s)
----------------------------------------------
1 10000 1.201231728 1.196311177
5 2000 1.065743872 1.040566424
10 1000 0.991054735 0.986876440
50 200 0.976554203 0.969608733
100 100 0.998504680 0.969218270
500 20 1.157347764 0.962602963
1000 10 1.619521852 1.085140172

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Reviewed-by: Paul Menage <menage@google.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
include/linux/cgroup.h
kernel/cgroup.c