From mboxrd@z Thu Jan 1 00:00:00 1970 From: OHMURA Kei Subject: Re: [Qemu-devel] Re: [PATCH v2] qemu-kvm: Speed up of the dirty-bitmap-traveling Date: Wed, 17 Feb 2010 18:42:53 +0900 Message-ID: <4B7BBA1D.2060703@lab.ntt.co.jp> References: <4B728FF9.6010707@lab.ntt.co.jp> <4B72B28E.6010801@redhat.com> <4B72D706.3070602@codemonkey.ws> <4B74B70A.4030805@lab.ntt.co.jp> <4B77EDC2.7000401@redhat.com> <4B78E5C5.80802@lab.ntt.co.jp> <247526C9-7810-4F4D-AE3D-C1A774FF6FFB@suse.de> <4B7A7E72.6060305@lab.ntt.co.jp> <2AB041C1-C6BC-41DD-B574-308B994C2B2B@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Avi Kivity , "qemu-devel@nongnu.org" , "kvm@vger.kernel.org" , mtosatti@redhat.com, drepper@redhat.com, Yoshiaki Tamura , ohmura.kei@lab.ntt.co.jp To: Alexander Graf Return-path: Received: from tama500.ecl.ntt.co.jp ([129.60.39.148]:42377 "EHLO tama500.ecl.ntt.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932854Ab0BQJnK (ORCPT ); Wed, 17 Feb 2010 04:43:10 -0500 In-Reply-To: <2AB041C1-C6BC-41DD-B574-308B994C2B2B@suse.de> Sender: kvm-owner@vger.kernel.org List-ID: >>> "We think"? I mean - yes, I think so too. But have you actually measured it? >>> How much improvement are we talking here? >>> Is it still faster when a bswap is involved? >> Thanks for pointing out. >> I will post the data for x86 later. >> However, I don't have a test environment to check the impact of bswap. >> Would you please measure the run time between the following section if possible? > > It'd make more sense to have a real stand alone test program, no? > I can try to write one today, but I have some really nasty important bugs to fix first. OK. I will prepare a test code with sample data. Since I found a ppc machine around, I will run the code and post the results of x86 and ppc. By the way, the following data is a result of x86 measured in QEMU/KVM. This data shows, how many times the function is called (#called), runtime of original function(orig.), runtime of this patch(patch), speedup ratio (ratio). Test1: Guest OS read 3GB file, which is bigger than memory. #called orig.(msec) patch(msec) ratio 108 1.1 0.1 7.6 102 1.0 0.1 6.8 132 1.6 0.2 7.1 Test2: Guest OS read/write 3GB file, which is bigger than memory. #called orig.(msec) patch(msec) ratio 2394 33 7.7 4.3 2100 29 7.1 4.1 2832 40 9.9 4.0