From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 12 Nov 2008 16:07:58 -0800 From: Andrew Morton Subject: Re: [RFC][PATCH 1/6] memcg: free all at rmdir Message-Id: <20081112160758.3dca0b22.akpm@linux-foundation.org> In-Reply-To: <20081112122656.c6e56248.kamezawa.hiroyu@jp.fujitsu.com> References: <20081112122606.76051530.kamezawa.hiroyu@jp.fujitsu.com> <20081112122656.c6e56248.kamezawa.hiroyu@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: KAMEZAWA Hiroyuki Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, balbir@linux.vnet.ibm.com, nishimura@mxp.nes.nec.co.jp, menage@google.com List-ID: On Wed, 12 Nov 2008 12:26:56 +0900 KAMEZAWA Hiroyuki wrote: > +5.1 on_rmdir > +set behavior of memcg at rmdir (Removing cgroup) default is "drop". > + > +5.1.1 drop > + #echo on_rmdir drop > memory.attribute > + This is default. All pages on the memcg will be freed. > + If pages are locked or too busy, they will be moved up to the parent. > + Useful when you want to drop (large) page caches used in this memcg. > + But some of in-use page cache can be dropped by this. > + > +5.1.2 keep > + #echo on_rmdir keep > memory.attribute > + All pages on the memcg will be moved to its parent. > + Useful when you don't want to drop page caches used in this memcg. > + You can keep page caches from some library or DB accessed by this > + memcg on memory. Would it not be more useful to implement a per-memcg version of /proc/sys/vm/drop_caches? (One without drop_caches' locking bug, hopefully). If we do this then we can make the above "keep" behaviour non-optional, and the operator gets to choose whether or not to drop the caches before doing the rmdir. Plus, we get a new per-memcg drop_caches capability. And it's a nicer interface, and it doesn't have the obvious races which on_rmdir has, etc. hm? -- 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/ . Don't email: email@kvack.org