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Re: [Qemu-devel] [PATCH RESEND v4 17/18] target-i386: block migration an
From: |
Marcelo Tosatti |
Subject: |
Re: [Qemu-devel] [PATCH RESEND v4 17/18] target-i386: block migration and savevm if invariant tsc is exposed |
Date: |
Fri, 16 May 2014 06:31:06 -0300 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Thu, May 15, 2014 at 02:17:11PM +0200, Juan Quintela wrote:
> Eduardo Habkost <address@hidden> wrote:
> > From: Marcelo Tosatti <address@hidden>
> >
> > Invariant TSC documentation mentions that "invariant TSC will run at a
> > constant rate in all ACPI P-, C-. and T-states".
> >
> > This is not the case if migration to a host with different TSC frequency
> > is allowed, or if savevm is performed. So block migration/savevm.
> >
> > Cc: Juan Quintela <address@hidden>
> > Signed-off-by: Marcelo Tosatti <address@hidden>
> > Reviewed-by: Eduardo Habkost <address@hidden>
> > Signed-off-by: Eduardo Habkost <address@hidden>
>
> Reviewed-by: Juan Quintela <address@hidden>
>
> I don't have a better suggestion. Really we could allow migration to
> identical machines, but I assume that there is not a way to read the tsc
> frequency?
> (Althought reading the model name/numbers could be enough?)
Even if migration to identical machine is performed, you would have
to perform timing of downtime to compensate.
> I.e. Add a subsection that includes the cpu model name, or whatever we
> can have to identify the host cpu?
"On processors with invariant TSC support, the OS may use the TSC for
wall clock timer services (instead of ACPI or HPET timers)."
- [Qemu-devel] [PATCH RESEND v4 13/18] target-i386: Support "-cpu host" in TCG mode, (continued)
[Qemu-devel] [PATCH RESEND v4 17/18] target-i386: block migration and savevm if invariant tsc is exposed, Eduardo Habkost, 2014/05/14
[Qemu-devel] [PATCH RESEND v4 18/18] target-i386: support "invariant tsc" flag, Eduardo Habkost, 2014/05/14
Re: [Qemu-devel] [PATCH RESEND v4 00/18] target-i386: CPU feature flag queue, Andreas Färber, 2014/05/14