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Re: [Qemu-devel] Para-Virtualized Clock Usage
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From: |
Marcelo Tosatti |
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Subject: |
Re: [Qemu-devel] Para-Virtualized Clock Usage |
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Date: |
Wed, 24 Apr 2013 05:27:48 -0300 |
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User-agent: |
Mutt/1.5.21 (2010-09-15) |
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.