From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rik van Riel Subject: Re: [RFC v2 4/7] change kernel accounting to include steal time Date: Mon, 30 Aug 2010 15:45:27 -0400 Message-ID: <4C7C0A57.2010906@redhat.com> References: <1283184391-7785-1-git-send-email-glommer@redhat.com> <1283184391-7785-2-git-send-email-glommer@redhat.com> <1283184391-7785-3-git-send-email-glommer@redhat.com> <1283184391-7785-4-git-send-email-glommer@redhat.com> <1283184391-7785-5-git-send-email-glommer@redhat.com> <1283184391-7785-6-git-send-email-glommer@redhat.com> <1283184391-7785-7-git-send-email-glommer@redhat.com> <1283184391-7785-8-git-send-email-glommer@redhat.com> <4C7BEA9C.1060605@goop.org> <4C7BFACD.4030409@redhat.com> <4C7C0187.7040401@goop.org> <4C7C03CB.1060700@redhat.com> <1283196005.1820.1340.camel@laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Jeremy Fitzhardinge , Glauber Costa , kvm@vger.kernel.org, avi@redhat.com, zamsden@redhat.com, mtosatti@redhat.com, mingo@elte.hu To: Peter Zijlstra Return-path: Received: from mx1.redhat.com ([209.132.183.28]:37102 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752718Ab0H3Tpi (ORCPT ); Mon, 30 Aug 2010 15:45:38 -0400 In-Reply-To: <1283196005.1820.1340.camel@laptop> Sender: kvm-owner@vger.kernel.org List-ID: On 08/30/2010 03:20 PM, Peter Zijlstra wrote: > On Mon, 2010-08-30 at 15:17 -0400, Rik van Riel wrote: >> >> When time is accounted as steal time, it is NOT accounted as >> to the current process user/system/..., which in turn should >> help it in the scheduler. >> >> Am I overlooking something? > > Yeah, the scheduler doesn't care about the user/system time accounting > at all... :-) Uh oh. This would seem like something we'll want to fix in an architecture independent way, so s390, etc. also benefit from it. I can see this being a real problem when the host and guest OS have the same time slice - which is quite possible since they may both be the same version of Linux. Guest 1, alternating between processes A and B, may end up with process A getting a lot of actual CPU time, and process B being scheduled in when the VCPU itself is not running... -- All rights reversed