From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH 0/3] Improved yield performance Date: Wed, 26 Feb 2014 16:16:00 +0100 Message-ID: <530E0530.3060809@redhat.com> References: <1393427659-42501-1-git-send-email-borntraeger@de.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Cc: Gleb Natapov , KVM , linux-s390 , Cornelia Huck , Michael Mueller To: Christian Borntraeger Return-path: Received: from mx1.redhat.com ([209.132.183.28]:26410 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750954AbaBZQcD (ORCPT ); Wed, 26 Feb 2014 11:32:03 -0500 In-Reply-To: <1393427659-42501-1-git-send-email-borntraeger@de.ibm.com> Sender: kvm-owner@vger.kernel.org List-ID: Il 26/02/2014 16:14, Christian Borntraeger ha scritto: > Paolo, > > here is the reworked yield heuristics series against kvm/queue with > your suggested changes. > > Attached is a minimized testcase that reproduces the performance > win (runtime 0:50 instead of 1:00). The constants and the setup > seem a bit artificial but these seem to reproduce the problem on my > test system: as soon as there is contention from other guests the > patch improves the runtime of belows testcase. The original test > had 8 competing guests with 4 cpus, I simplified that a bit to have > one big guest as cpu stealer. > > host 20 cpus > GUEST1 (20vCPUS) GUEST2(40vCPUS) > runs the test all 40 CPUs cpu bound > > > The testcase stresses the IPC system call, since that creates a lot > of diag44 exits on s390 if contended. > > Some other spinlock tests like fio on guest tmpfs seem to be unaffected. > > Please consider for kvm/queue. If you have some performance tests > a regression run on x86 is welcome. Yes, will apply as soon as kvm/queue moves to kvm/next (1 hour or so). Paolo