Try to reduce overheads in moving swap charge by:
- Adds a new function(__mem_cgroup_put), which takes "count" as a arg and
decrement mem->refcnt by "count".
- Removed res_counter_uncharge, css_put, and mem_cgroup_put from the path
of moving swap account, and consolidate all of them into mem_cgroup_clear_mc.
We cannot do that about mc.to->refcnt.
These changes reduces the overhead from 1.35sec to 0.9sec to move charges
of 1G anonymous memory(including 500MB swap) in my test environment.
Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
483c30b514