From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:50267) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UUW9O-0000Da-2M for qemu-devel@nongnu.org; Tue, 23 Apr 2013 01:52:23 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UUW9M-0000hv-PE for qemu-devel@nongnu.org; Tue, 23 Apr 2013 01:52:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:3431) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UUW9M-0000hr-Hh for qemu-devel@nongnu.org; Tue, 23 Apr 2013 01:52:20 -0400 Date: Tue, 23 Apr 2013 08:52:16 +0300 From: Gleb Natapov Message-ID: <20130423055215.GA12401@redhat.com> References: <375D787373987F47B9BF5BA875F1ED8818450330@xmb-rcd-x04.cisco.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <375D787373987F47B9BF5BA875F1ED8818450330@xmb-rcd-x04.cisco.com> Subject: Re: [Qemu-devel] Para-Virtualized Clock Usage List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Joji Mekkattuparamban (joji)" Cc: mtosatti@redhat.com, "qemu-devel@nongnu.org" , kvm@vger.kernel.org On Mon, Apr 22, 2013 at 04:58:01PM +0000, Joji Mekkattuparamban (joji) wrote: > Greetings, > > I have a SMP guest application, running on the 2.6.27 Linux kernel. The application, originally written for bare metal, makes extensive use of the TSC, by directly invoking rdtsc from the user space for timestamp purposes. While running on KVM (RHEL version 6.3), we are running into TSC issues on some hardware. As a solution, I am considering migrating to the pvclock. I am wondering if there is an example for migrating from TSC to the pvclock. Any pointers? > Wrong list, you should ask KVM (copied). Recent kernels have pvclock vdso support which means that gettimeofday() uses it without entering the kernel. Marcelo? -- Gleb.