Thread (20 messages) 20 messages, 3 authors, 2012-01-25

Re: [PATCH v3] memcg: remove PCG_CACHE page_cgroup flag

From: Michal Hocko <hidden>
Date: 2012-01-20 08:45:48
Also in: lkml

On Fri 20-01-12 12:26:58, KAMEZAWA Hiroyuki wrote:
I think this version is much simplified.

==
From 5700a4fe9c581e1ebaa021ba6119dc8d921b024f Mon Sep 17 00:00:00 2001
From: KAMEZAWA Hiroyuki <redacted>
Date: Thu, 19 Jan 2012 17:09:41 +0900
Subject: [PATCH v3] memcg: remove PCG_CACHE

We record 'the page is cache' by PCG_CACHE bit to page_cgroup.
Here, "CACHE" means anonymous user pages (and SwapCache). This
doesn't include shmem.

Consdering callers, at charge/uncharge, the caller should know
what  the page is and we don't need to record it by using 1bit
per page.

This patch removes PCG_CACHE bit and make callers of
mem_cgroup_charge_statistics() to specify what the page is.

Changelog since v2
 - removed 'not_rss', added 'anon'
 - changed a meaning of arguments to mem_cgroup_charge_statisitcs()
 - removed a patch to mem_cgroup_uncharge_cache
 - simplified comment.

Changelog since RFC.
 - rebased onto memcg-devel
 - rename 'file' to 'not_rss'
 - some cleanup and added comment.

Signed-off-by: KAMEZAWA Hiroyuki <redacted>
---
 include/linux/page_cgroup.h |    8 +------
 mm/memcontrol.c             |   48 +++++++++++++++++++++++-------------------
 2 files changed, 27 insertions(+), 29 deletions(-)
[...]
quoted hunk ↗ jump to hunk
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index ff24520..f000c82 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -672,15 +672,19 @@ static unsigned long mem_cgroup_read_events(struct mem_cgroup *memcg,
 }
 
 static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg,
-					 bool file, int nr_pages)
+					 bool rss, int nr_pages)
Can we make this anon as well?
 {
 	preempt_disable();
 
-	if (file)
-		__this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_CACHE],
+	/*
+	 * Here, RSS means 'mapped anon' and anon's SwapCache. Shmem/tmpfs is
+	 * counted as CACHE even if it's on ANON LRU.
+	 */
+	if (rss)
+		__this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_RSS],
 				nr_pages);
 	else
-		__this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_RSS],
+		__this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_CACHE],
 				nr_pages);
 
 	/* pagein of a big page is an event. So, ignore page size */
[...]

-- 
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9    
Czech Republic

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