From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx185.postini.com [74.125.245.185]) by kanga.kvack.org (Postfix) with SMTP id E9BDC6B005D for ; Wed, 26 Sep 2012 05:04:26 -0400 (EDT) Date: Wed, 26 Sep 2012 10:03:43 +0100 From: "Daniel P. Berrange" Subject: Re: [RFC 2/4] memcg: make it suck faster Message-ID: <20120926090343.GB31968@redhat.com> Reply-To: "Daniel P. Berrange" References: <1348563173-8952-1-git-send-email-glommer@parallels.com> <1348563173-8952-3-git-send-email-glommer@parallels.com> <20120925140236.b0b089e7.akpm@linux-foundation.org> <5062C281.4080805@parallels.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <5062C281.4080805@parallels.com> Sender: owner-linux-mm@kvack.org List-ID: To: Glauber Costa Cc: Andrew Morton , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, devel@openvz.org, Peter Zijlstra , Michal Hocko , Kamezawa Hiroyuki , Johannes Weiner , Mel Gorman On Wed, Sep 26, 2012 at 12:53:21PM +0400, Glauber Costa wrote: > On 09/26/2012 01:02 AM, Andrew Morton wrote: > >> nomemcg : memcg compile disabled. > >> > base : memcg enabled, patch not applied. > >> > bypassed : memcg enabled, with patch applied. > >> > > >> > base bypassed > >> > User 109.12 105.64 > >> > System 1646.84 1597.98 > >> > Elapsed 229.56 215.76 > >> > > >> > nomemcg bypassed > >> > User 104.35 105.64 > >> > System 1578.19 1597.98 > >> > Elapsed 212.33 215.76 > >> > > >> > So as one can see, the difference between base and nomemcg in terms > >> > of both system time and elapsed time is quite drastic, and consistent > >> > with the figures shown by Mel Gorman in the Kernel summit. This is a > >> > ~ 7 % drop in performance, just by having memcg enabled. memcg functions > >> > appear heavily in the profiles, even if all tasks lives in the root > >> > memcg. > >> > > >> > With bypassed kernel, we drop this down to 1.5 %, which starts to fall > >> > in the acceptable range. More investigation is needed to see if we can > >> > claim that last percent back, but I believe at last part of it should > >> > be. > > Well that's encouraging. I wonder how many users will actually benefit > > from this - did I hear that major distros are now using memcg in some > > system-infrastructure-style code? > > > > If they do, they actually be come "users of memcg". This here is aimed > at non-users of memcg, which given all the whining about it, it seems to > be plenty. > > Also, I noticed, for instance, that libvirt is now creating memcg > hierarchies for lxc and qemu as placeholders, before you actually create > any vm or container. This is mostly just lazyness on our part. There's no technical reason why we can't delay creating our intermediate cgroups until we actually have a VM ready to start, it was just simpler to create them when we started the main daemon. Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :| -- 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