[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] Exporting kvm_max_guest_tsc_khz to userspace (was Re: [
From: |
Eduardo Habkost |
Subject: |
Re: [Qemu-devel] Exporting kvm_max_guest_tsc_khz to userspace (was Re: [PATCH 4/4] kvm: Allow migration with invtsc) |
Date: |
Wed, 11 Jan 2017 11:26:53 -0200 |
User-agent: |
Mutt/1.7.1 (2016-10-04) |
On Mon, Jan 09, 2017 at 03:58:11PM +0100, Paolo Bonzini wrote:
>
>
> On 08/01/2017 21:28, Eduardo Habkost wrote:
> >> Well just export KVM_GET_TSC_KHZ in a QMP command right? Its pretty
> >> easy.
> >>
> >> Let me know if you need any help coding or testing.
> > I just found out that KVM doesn't provide something that QEMU and
> > libvirt need: the value of kvm_max_guest_tsc_khz. Without it, we
> > have no way to know if a given VM is really migratable to a host.
> >
> > Could we add a KVM_CAP_MAX_TSC_KHZ capability for that?
>
> The ratio is really quite high, 256x the host frequency for AMD and
> 65536x for Intel. Anything below 2^32 Hz (above that, there would
> probably be other failures) is safe.
2^32 Hz (~4.3 GHz) sounds like a limit likely to be hit by future
CPUs. Which kind of failures do you think we could see?
--
Eduardo
- Re: [Qemu-devel] [libvirt] TSC frequency configuration & invtsc migration (was Re: [PATCH 4/4] kvm: Allow migration with invtsc), (continued)
- Re: [Qemu-devel] [libvirt] TSC frequency configuration & invtsc migration (was Re: [PATCH 4/4] kvm: Allow migration with invtsc), Daniel P. Berrange, 2017/01/05
- Re: [Qemu-devel] [libvirt] TSC frequency configuration & invtsc migration (was Re: [PATCH 4/4] kvm: Allow migration with invtsc), Eduardo Habkost, 2017/01/05
- Re: [Qemu-devel] [libvirt] TSC frequency configuration & invtsc migration (was Re: [PATCH 4/4] kvm: Allow migration with invtsc), Daniel P. Berrange, 2017/01/05
- Re: [Qemu-devel] [libvirt] TSC frequency configuration & invtsc migration (was Re: [PATCH 4/4] kvm: Allow migration with invtsc), Eduardo Habkost, 2017/01/05
- Re: [Qemu-devel] [libvirt] TSC frequency configuration & invtsc migration (was Re: [PATCH 4/4] kvm: Allow migration with invtsc), Paolo Bonzini, 2017/01/10
- Re: [Qemu-devel] TSC frequency configuration & invtsc migration (was Re: [PATCH 4/4] kvm: Allow migration with invtsc), Marcelo Tosatti, 2017/01/06
- [Qemu-devel] How to make dest host abort migration safely (was Re: [PATCH 4/4] kvm: Allow migration with invtsc), Eduardo Habkost, 2017/01/08
- Re: [Qemu-devel] How to make dest host abort migration safely (was Re: [PATCH 4/4] kvm: Allow migration with invtsc), Dr. David Alan Gilbert, 2017/01/09
- [Qemu-devel] Exporting kvm_max_guest_tsc_khz to userspace (was Re: [PATCH 4/4] kvm: Allow migration with invtsc), Eduardo Habkost, 2017/01/08
- Re: [Qemu-devel] Exporting kvm_max_guest_tsc_khz to userspace (was Re: [PATCH 4/4] kvm: Allow migration with invtsc), Paolo Bonzini, 2017/01/09
- Re: [Qemu-devel] Exporting kvm_max_guest_tsc_khz to userspace (was Re: [PATCH 4/4] kvm: Allow migration with invtsc),
Eduardo Habkost <=
- Re: [Qemu-devel] Exporting kvm_max_guest_tsc_khz to userspace (was Re: [PATCH 4/4] kvm: Allow migration with invtsc), Paolo Bonzini, 2017/01/11
- Re: [Qemu-devel] TSC frequency configuration & invtsc migration (was Re: [PATCH 4/4] kvm: Allow migration with invtsc), Paolo Bonzini, 2017/01/10
- Re: [Qemu-devel] TSC frequency configuration & invtsc migration (was Re: [PATCH 4/4] kvm: Allow migration with invtsc), Eduardo Habkost, 2017/01/11
- Re: [Qemu-devel] TSC frequency configuration & invtsc migration (was Re: [PATCH 4/4] kvm: Allow migration with invtsc), Marcelo Tosatti, 2017/01/18
- Re: [Qemu-devel] TSC frequency configuration & invtsc migration (was Re: [PATCH 4/4] kvm: Allow migration with invtsc), Eduardo Habkost, 2017/01/18