From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH v2 00/11] KVM in-guest performance monitoring Date: Thu, 16 Jun 2011 19:31:04 +0300 Message-ID: <4DFA2FC8.4080704@redhat.com> References: <1307972106-2468-1-git-send-email-avi@redhat.com> <4DF66B1A.6060606@cisco.com> <4DF71DA3.2080300@redhat.com> <4DF7972F.3040103@cisco.com> <4DF79941.9050705@siemens.com> <4DF79B6F.10102@cisco.com> <4DF79EFE.1050201@cisco.com> <4DF7A436.8090308@cisco.com> <4DF873FD.6040903@redhat.com> <4DF8A82F.5090900@cisco.com> <4DF8B1F8.6030502@redhat.com> <4DF8D8FE.2080808@cisco.com> <4DF8DD87.8040905@redhat.com> <4DF8E328.6070708@cisco.com> <4DFA0AC4.9050702@redhat.com> <4DFA0E56.70301@cisco.com> <1308236915.13240.66.camel@twins> <4DFA1F18.4090903@cisco.com> <1308238021.13240.84.camel@twins> <4DFA229A.1030004@cisco.com> <4DFA286A.1030006@redhat.com> <4DFA298B.9020206@cisco.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Peter Zijlstra , Marcelo Tosatti , kvm@vger.kernel.org, Ingo Molnar , Arnaldo Carvalho de Melo To: David Ahern Return-path: Received: from mx1.redhat.com ([209.132.183.28]:22970 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756832Ab1FPRHM (ORCPT ); Thu, 16 Jun 2011 13:07:12 -0400 In-Reply-To: <4DFA298B.9020206@cisco.com> Sender: kvm-owner@vger.kernel.org List-ID: On 06/16/2011 07:04 PM, David Ahern wrote: > > On 06/16/2011 09:59 AM, Avi Kivity wrote: > > On 06/16/2011 06:34 PM, David Ahern wrote: > >> > > >> > main () > >> > { > >> > int i; > >> > > >> > fork(); > >> > fork(); > > > > What happens without the two forks? > > > > you have a 1-billion instruction benchmark since there is only 1 process. > I mean in terms of the overhead. Is the overhead due to context switches being made more expensive by the pmu, or is it something else? But there were only 337 context switches in your measurement, they couldn't possibly be so bad. Anyway I'll investigate it. -- error compiling committee.c: too many arguments to function