From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx162.postini.com [74.125.245.162]) by kanga.kvack.org (Postfix) with SMTP id C3DA26B0081 for ; Fri, 27 Apr 2012 20:01:24 -0400 (EDT) Received: by vbbey12 with SMTP id ey12so1278320vbb.14 for ; Fri, 27 Apr 2012 17:01:23 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <4F9A327A.6050409@jp.fujitsu.com> <4F9A359C.10107@jp.fujitsu.com> Date: Sat, 28 Apr 2012 09:01:23 +0900 Message-ID: Subject: Re: [RFC][PATCH 5/9 v2] move charges to root at rmdir if use_hierarchy is unset From: Hiroyuki Kamezawa Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: Ying Han Cc: KAMEZAWA Hiroyuki , Linux Kernel , "linux-mm@kvack.org" , "cgroups@vger.kernel.org" , Michal Hocko , Johannes Weiner , Frederic Weisbecker , Glauber Costa , Tejun Heo , "Aneesh Kumar K.V" , Andrew Morton On Sat, Apr 28, 2012 at 4:12 AM, Ying Han wrote: > On Thu, Apr 26, 2012 at 10:58 PM, KAMEZAWA Hiroyuki > wrote: >> Now, at removal of cgroup, ->pre_destroy() is called and move charges >> to the parent cgroup. A major reason of -EBUSY returned by ->pre_destroy= () >> is that the 'moving' hits parent's resource limitation. It happens only >> when use_hierarchy=3D0. This was a mistake of original design.(it's me..= .) > > Nice patch, i can see how broken it is now with use_hierarchy=3D0... > > nitpick on the documentation below: > >> >> Considering use_hierarchy=3D0, all cgroups are treated as flat. So, no o= ne >> cannot justify moving charges to parent...parent and children are in >> flat configuration, not hierarchical. >> >> This patch modifes to move charges to root cgroup at rmdir/force_empty >> if use_hierarchy=3D=3D0. This will much simplify rmdir() and reduce erro= r >> in ->pre_destroy. >> >> Signed-off-by: KAMEZAWA Hiroyuki >> --- >> =A0Documentation/cgroups/memory.txt | =A0 12 ++++++---- >> =A0mm/memcontrol.c =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0| =A0 39 +++++++++= ++++------------------------ >> =A02 files changed, 21 insertions(+), 30 deletions(-) >> >> diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/me= mory.txt >> index 54c338d..82ce1ef 100644 >> --- a/Documentation/cgroups/memory.txt >> +++ b/Documentation/cgroups/memory.txt >> @@ -393,14 +393,14 @@ cgroup might have some charge associated with it, = even though all >> =A0tasks have migrated away from it. (because we charge against pages, n= ot >> =A0against tasks.) >> >> -Such charges are freed or moved to their parent. At moving, both of RSS >> -and CACHES are moved to parent. >> -rmdir() may return -EBUSY if freeing/moving fails. See 5.1 also. >> +Such charges are freed or moved to their parent if use_hierarchy=3D1. >> +if use_hierarchy=3D0, the charges will be moved to root cgroup. > > It is more clear that we move the stats to root (if use_hierarchy=3D=3D0) > or parent (if use_hierarchy=3D=3D1), and no change on the charge except > uncharging from the child. > Seems nicer. I'll use your text in next ver. Thanks, -Kame -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org