From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Sat, 28 Jun 2008 13:36:15 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [RFC 0/5] Memory controller soft limit introduction (v3) Message-Id: <20080628133615.a5fa16cf.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20080627151808.31664.36047.sendpatchset@balbir-laptop> References: <20080627151808.31664.36047.sendpatchset@balbir-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Balbir Singh Cc: Andrew Morton , YAMAMOTO Takashi , Paul Menage , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Fri, 27 Jun 2008 20:48:08 +0530 Balbir Singh wrote: > This patchset implements the basic changes required to implement soft limits > in the memory controller. A soft limit is a variation of the currently > supported hard limit feature. A memory cgroup can exceed it's soft limit > provided there is no contention for memory. > > These patches were tested on a x86_64 box, by running a programs in parallel, > and checking their behaviour for various soft limit values. > > These patches were developed on top of 2.6.26-rc5-mm3. Comments, suggestions, > criticism are all welcome! > > A previous version of the patch can be found at > > http://kerneltrap.org/mailarchive/linux-kernel/2008/2/19/904114 > I have a couple of comments. 1. Why you add soft_limit to res_coutner ? Is there any other controller which uses soft-limit ? I'll move watermark handling to memcg from res_counter becasue it's required only by memcg. 2. *please* handle NUMA There is a fundamental difference between global VMM and memcg. global VMM - reclaim memory at memory shortage. memcg - for reclaim memory at memory limit Then, memcg wasn't required to handle place-of-memory at hitting limit. *just reducing the usage* was enough. In this set, you try to handle memory shortage handling. So, please handle NUMA, i.e. "what node do you want to reclaim memory from ?" If not, - memory placement of Apps can be terrible. - cannot work well with cpuset. (I think) 3. I think when "mem_cgroup_reclaim_on_contention" exits is unclear. plz add explanation of algorithm. It returns when some pages are reclaimed ? 4. When swap-full cgroup is on the top of heap, which tends to contain tons of memory, much amount of cpu-time will be wasted. Can we add "ignore me" flag ? Maybe "2" is the most important to implement this. I think this feature itself is interesting, so please handle NUMA. "4" includes the user's (middleware's) memcg handling problem. But maybe a problem should be fixed in future. 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/ . Don't email: email@kvack.org