From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kamezawa Hiroyuki Subject: Re: [RFC] memory cgroup: my thoughts on memsw Date: Thu, 11 Sep 2014 10:22:51 +0900 Message-ID: <5410F96B.1020308@jp.fujitsu.com> References: <20140904143055.GA20099@esperanza> <5408E1CD.3090004@jp.fujitsu.com> <20140905082846.GA25641@esperanza> <5409C6BB.7060009@jp.fujitsu.com> <20140905160029.GF25641@esperanza> <540A4420.2030504@jp.fujitsu.com> <20140908110131.GA11812@esperanza> <540DB4EC.6060100@jp.fujitsu.com> <20140910120157.GA13796@esperanza> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20140910120157.GA13796@esperanza> Sender: owner-linux-mm@kvack.org List-ID: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Vladimir Davydov Cc: Johannes Weiner , Michal Hocko , Greg Thelen , Hugh Dickins , Motohiro Kosaki , Glauber Costa , Tejun Heo , Andrew Morton , Pavel Emelianov , Konstantin Khorenko , LKML-MM , LKML-cgroups , LKML (2014/09/10 21:01), Vladimir Davydov wrote: > On Mon, Sep 08, 2014 at 10:53:48PM +0900, Kamezawa Hiroyuki wrote: >> (2014/09/08 20:01), Vladimir Davydov wrote: >>> On Sat, Sep 06, 2014 at 08:15:44AM +0900, Kamezawa Hiroyuki wrote: >>>> As you noticed, hitting anon+swap limit just means oom-kill. >>>> My point is that using oom-killer for "server management" just seems crazy. >>>> >>>> Let my clarify things. your proposal was. >>>> 1. soft-limit will be a main feature for server management. >>>> 2. Because of soft-limit, global memory reclaim runs. >>>> 3. Using swap at global memory reclaim can cause poor performance. >>>> 4. So, making use of OOM-Killer for avoiding swap. >>>> >>>> I can't agree "4". I think >>>> >>>> - don't configure swap. >>> >>> Suppose there are two containers, each having soft limit set to 50% of >>> total system RAM. One of the containers eats 90% of the system RAM by >>> allocating anonymous pages. Another starts using file caches and wants >>> more than 10% of RAM to work w/o issuing disk reads. So what should we >>> do then? >>> We won't be able to shrink the first container to its soft >>> limit, because there's no swap. Leaving it as is would be unfair from >>> the second container's point of view. Kill it? But the whole system is >>> going OK, because the working set of the second container is easily >>> shrinkable. Besides there may be some progress in shrinking file caches >> >from the first container. >>> >>>> - use zram >>> >>> In fact this isn't different from the previous proposal (working w/o >>> swap). ZRAM only compresses data while still storing them in RAM so we >>> eventually may get into a situation where almost all RAM is full of >>> compressed anon pages. >>> >> >> In above 2 cases, "vmpressure" works fine. > > What if a container allocates memory so fast that the userspace thread > handling its threshold notifications won't have time to react before it > eats all memory? > Softlimit is for avoiding such unfair memory scheduling, isn't it ? 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