From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [RFC 4/7] change kernel accounting to include steal time Date: Sun, 29 Aug 2010 12:59:36 +0300 Message-ID: <4C7A2F88.6050807@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> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, zamsden@redhat.com, mtosatti@redhat.com, riel@redhat.com To: Glauber Costa Return-path: Received: from mx1.redhat.com ([209.132.183.28]:33018 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752992Ab0H2J7h (ORCPT ); Sun, 29 Aug 2010 05:59:37 -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 o7T9xb9N027964 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Sun, 29 Aug 2010 05:59:37 -0400 Received: from cleopatra.tlv.redhat.com (cleopatra.tlv.redhat.com [10.35.255.11]) by int-mx03.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id o7T9xadl010823 for ; Sun, 29 Aug 2010 05:59:37 -0400 In-Reply-To: <1282772597-4183-5-git-send-email-glommer@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 08/26/2010 12:43 AM, Glauber Costa wrote: > This patch proposes a common steal time implementation. When no > steal time is accounted, we just add a branch to the current > accounting code, that shouldn't add much overhead. > > When we do want to register steal time, we proceed as following: > - if we would account user or system time in this tick, and there is > out-of-cpu time registered, we skip it altogether, and account steal > time only. > - if we would account user or system time in this tick, and we got the > cpu for the whole slice, we proceed normaly. > - if we are idle in this tick, we flush out-of-cpu time to give it the > chance to update whatever last-measure internal variable it may have. > > This approach is simple, but proved to work well for my test scenarios. > in a UP guest on UP host, with a cpu-hog in both guest and host shows > ~ 50 % steal time. steal time is also accounted proportionally, if > nice values are given to the host cpu-hog. > > A cpu-hog in the host with no load in the guest, produces 0 % steal time, > with 100 % idle, as one would expect. > The scheduler people and lkml need to be copied on this patch. Since s390 does steal time (I think?), can this code be shared? -- error compiling committee.c: too many arguments to function