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Date: Wed, 24 Apr 2013 05:27:48 -0300
From: Marcelo Tosatti <mtosatti@redhat.com>
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Subject: Re: [Qemu-devel] Para-Virtualized Clock Usage
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To: Gleb Natapov <gleb@redhat.com>
Cc: "Joji Mekkattuparamban (joji)" <joji@cisco.com>, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>, kvm@vger.kernel.org

On Tue, Apr 23, 2013 at 08:52:16AM +0300, Gleb Natapov wrote:
> 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.

Converting application to make use of gettimeofday() should be the
best way to make use of pvclock, yes.