From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: problem wit svm_get_msr on kvm-kmod-2.6.31.6 Date: Tue, 17 Nov 2009 10:59:16 +0100 Message-ID: <4B0273F4.8030204@siemens.com> References: <90D306BE6EBC8D428A824FBBA7A3113D014275E0F0@ronja.maurer-it.com> <4B012709.20508@redhat.com> <90D306BE6EBC8D428A824FBBA7A3113D014275E0F2@ronja.maurer-it.com> <4B012EDF.7030109@redhat.com> <90D306BE6EBC8D428A824FBBA7A3113D014275E0F5@ronja.maurer-it.com> <4B013F2A.2040900@redhat.com> <4B013FA1.4050003@siemens.com> <90D306BE6EBC8D428A824FBBA7A3113D014275E101@ronja.maurer-it.com> <4B0271DC.7090708@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Dietmar Maurer , kvm To: Avi Kivity , Joerg Roedel Return-path: Received: from goliath.siemens.de ([192.35.17.28]:17903 "EHLO goliath.siemens.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753541AbZKQJ73 (ORCPT ); Tue, 17 Nov 2009 04:59:29 -0500 In-Reply-To: <4B0271DC.7090708@siemens.com> Sender: kvm-owner@vger.kernel.org List-ID: Jan Kiszka wrote: > Dietmar Maurer wrote: >> Hi Jan, >> >> The ubuntu code puts some barrier around the read. >> >> http://kernel.ubuntu.com/git?p=ubuntu/ubuntu-hardy.git;a=commitdiff;h=198b348d96c9769153e72ca2461f8d841ddff1cc >> >> You simply override this with your own code - without barrier. Do you think this is correct? > > Unless I messed it up again, I "overwrote" it with what is in latest > mainline regarding native_read_tsc. But I will check once more. The removal of those barriers came with 0d12cdd5f883f508d33b85c1bae98fa28987c8c7 (sched: improve sched_clock() performance). So this is now an upstream question: Do we bother about the precision of native_read_tsc in svm or not? Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux