From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rik van Riel Subject: Re: [RFC 4/7] change kernel accounting to include steal time Date: Thu, 26 Aug 2010 17:05:24 -0400 Message-ID: <4C76D714.4040105@redhat.com> References: <1282772597-4183-1-git-send-email-glommer@redhat.com> <1282772597-4183-2-git-send-email-glommer@redhat.com> <1282772597-4183-3-git-send-email-glommer@redhat.com> <1282772597-4183-4-git-send-email-glommer@redhat.com> <1282772597-4183-5-git-send-email-glommer@redhat.com> <20100826172303.GB21273@amt.cnet> <20100826202856.GC2985@mothafucka.localdomain> <20100826204712.GA3773@amt.cnet> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Glauber Costa , kvm@vger.kernel.org, avi@redhat.com, zamsden@redhat.com To: Marcelo Tosatti Return-path: Received: from mx1.redhat.com ([209.132.183.28]:55180 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752978Ab0HZVF0 (ORCPT ); Thu, 26 Aug 2010 17:05:26 -0400 Received: from int-mx03.intmail.prod.int.phx2.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.16]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o7QL5QT0024040 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Thu, 26 Aug 2010 17:05:26 -0400 In-Reply-To: <20100826204712.GA3773@amt.cnet> Sender: kvm-owner@vger.kernel.org List-ID: On 08/26/2010 04:47 PM, Marcelo Tosatti wrote: > On Thu, Aug 26, 2010 at 05:28:56PM -0300, Glauber Costa wrote: >> On Thu, Aug 26, 2010 at 02:23:03PM -0300, Marcelo Tosatti wrote: >>> Skipping accounting of user/system time whenever there's any stolen >>> time detected probably breaks u/s accounting on non-cpu-hog loads. Steal time does not completely skip accounting of user/system time. Say that it has been 10ms since the last timer tick, we are currently in user mode, and 4ms have been accounted as steal time. The steal time accounting code will then account 4ms as steal time, and 6ms as user time. It does not "skip accounting of user/system time" at all. >> I am willing to test some workloads you can suggest, but right now, >> (yeah, I mostly used cpu-hogs), this scheme worked better. >> >> Linux does statistical sampling for accounting anyway, so I don't see >> it getting much worse. > > A "cpu hog" that sleeps 1us every 1ms. This kind of program can be an issue with or without steal time. I don't see steal time make the situation any worse. -- All rights reversed