From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx204.postini.com [74.125.245.204]) by kanga.kvack.org (Postfix) with SMTP id 9BBEE6B0006 for ; Fri, 19 Apr 2013 23:35:33 -0400 (EDT) Received: by mail-vc0-f175.google.com with SMTP id lf11so2373183vcb.34 for ; Fri, 19 Apr 2013 20:35:32 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20130420004221.GB17179@mtj.dyndns.org> References: <20130420002620.GA17179@mtj.dyndns.org> <20130420004221.GB17179@mtj.dyndns.org> From: Greg Thelen Date: Fri, 19 Apr 2013 20:35:12 -0700 Message-ID: Subject: Re: memcg: softlimit on internal nodes Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Tejun Heo Cc: Michal Hocko , Johannes Weiner , Balbir Singh , KAMEZAWA Hiroyuki , cgroups@vger.kernel.org, "linux-mm@kvack.org" , Hugh Dickins , Ying Han , Glauber Costa , Michel Lespinasse On Fri, Apr 19, 2013 at 5:42 PM, Tejun Heo wrote: > On Fri, Apr 19, 2013 at 05:26:20PM -0700, Tejun Heo wrote: >> If such actual soft limit is desired (I don't know, it just seems like >> a very fundamental / logical feature to me), please don't try to >> somehow overload "softlimit". They are two fundamentally different >> knobs, both make sense in their own ways, and when you stop confusing >> the two, there's nothing ambiguous about what what each knob means in >> hierarchical situations. This goes the same for the "untrusted" flag >> Ying told me, which seems like another confused way to overload two >> meanings onto "softlimit". Don't overload! > > As for how actually to clean up this yet another mess in memcg, I > don't know. Maybe introduce completely new knobs - say, > oom_threshold, reclaim_threshold, and reclaim_trigger - and alias > hardlimit to oom_threshold and softlimit to recalim_trigger? BTW, > "softlimit" should default to 0. Nothing else makes any sense. I agree that the hard limit could be called the oom_threshold. The meaning of the term reclaim_threshold is not obvious to me. I'd prefer to call the soft limit a reclaim_target. System global pressure can steal memory from a cgroup until its usage drops to the soft limit (aka reclaim_target). Pressure will try to avoid stealing memory below the reclaim target. The soft limit (reclaim_target) is not checked until global pressure exists. Currently we do not have a knob to set a reclaim_threshold, such that when usage exceeds the reclaim_threshold async reclaim is queued. We are not discussing triggering anything when soft limit is exceeded. -- 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