From mboxrd@z Thu Jan 1 00:00:00 1970 From: Victor fernandez Subject: Lost of performance over AMD-V with KVM? Date: Tue, 09 Jul 2013 14:20:43 +0200 Message-ID: <51DC001B.2010703@usc.es> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE To: kvm@vger.kernel.org Return-path: Received: from correo2.usc.es ([193.144.75.22]:37106 "EHLO correo2.usc.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752063Ab3GIMac (ORCPT ); Tue, 9 Jul 2013 08:30:32 -0400 Received: from [172.16.57.58] (pi057058.inv.usc.es [172.16.57.58]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by fpsunae2.usc.es (Postfix) with ESMTP id 5FAD7233B5B for ; Tue, 9 Jul 2013 14:20:44 +0200 (CEST) Sender: kvm-owner@vger.kernel.org List-ID: Hi EveryBody! recently, we have tested some specific High Energy Physics benchmarks t= hat was running over S.L.6 and we observed that the performance over AMD machines was really bad, about 30-40% lost. We were investigating and we conclude that the problem was with some cpu flags. These cpu flags are important for running our application because it is optimazed for running with them. So, we tuning our KVM with the name of flags parameters and with "-cpu host" parameter too, but we observed that the flags that we needed, they weren't included when we started the S.L.6 instance. We try to solve it, but when we conclude that the specific flags weren't included in the code of the last=20 versions of KVM and LibVirt(capabilities). Do you know something about this problem or you are aware of this? Thanks in advance, V=EDctor Fdez.