From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH RFC 1/2] kvm: Handle undercommitted guest case in PLE handler Date: Thu, 04 Oct 2012 17:00:28 +0200 Message-ID: <506DA48C.8050200@redhat.com> References: <20120921115942.27611.67488.sendpatchset@codeblue> <20120921120000.27611.71321.sendpatchset@codeblue> <505C654B.2050106@redhat.com> <505CA2EB.7050403@linux.vnet.ibm.com> <50607F1F.2040704@redhat.com> <20121003122209.GA9076@linux.vnet.ibm.com> <506C7057.6000102@redhat.com> <506D69AB.7020400@linux.vnet.ibm.com> <506D83EE.2020303@redhat.com> <1349356038.14388.3.camel@twins> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Raghavendra K T , Rik van Riel , "H. Peter Anvin" , Ingo Molnar , Marcelo Tosatti , Srikar , "Nikunj A. Dadhania" , KVM , Jiannan Ouyang , chegu vinod , "Andrew M. Theurer" , LKML , Srivatsa Vaddagiri , Gleb Natapov To: Peter Zijlstra Return-path: Received: from mx1.redhat.com ([209.132.183.28]:24909 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965200Ab2JDPBF (ORCPT ); Thu, 4 Oct 2012 11:01:05 -0400 In-Reply-To: <1349356038.14388.3.camel@twins> Sender: kvm-owner@vger.kernel.org List-ID: On 10/04/2012 03:07 PM, Peter Zijlstra wrote: > On Thu, 2012-10-04 at 14:41 +0200, Avi Kivity wrote: >> >> Again the numbers are ridiculously high for arch_local_irq_restore. >> Maybe there's a bad perf/kvm interaction when we're injecting an >> interrupt, I can't believe we're spending 84% of the time running the >> popf instruction. > > Smells like a software fallback that doesn't do NMI, hrtimer based > sampling typically hits popf where we re-enable interrupts. Good nose, that's probably it. Raghavendra, can you ensure that the PMU is properly exposed? 'dmesg' in the guest will tell. If it isn't, -cpu host will expose it (and a good idea anyway to get best performance). -- error compiling committee.c: too many arguments to function