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[Qemu-devel] Exporting kvm_max_guest_tsc_khz to userspace (was Re: [PATC
From: |
Eduardo Habkost |
Subject: |
[Qemu-devel] Exporting kvm_max_guest_tsc_khz to userspace (was Re: [PATCH 4/4] kvm: Allow migration with invtsc) |
Date: |
Sun, 8 Jan 2017 18:28:51 -0200 |
User-agent: |
Mutt/1.7.1 (2016-10-04) |
On Fri, Jan 06, 2017 at 08:31:27AM -0200, Marcelo Tosatti wrote:
[...]
> > >
> > > > Maybe your use case just needs a explicit "invtsc-migration=on"
> > > > command-line flag without a mechanism to abort migration on
> > > > mismatch? I can't tell.
> > >
> > > Again, there is no special case.
> > >
> > > > Note that even if we follow your suggestion and implement an
> > > > alternative version of patch 4/4 to cover your use case, I will
> > > > strongly recommend libvirt developers to support configuring TSC
> > > > frequency if they want to support invtsc + migration without
> > > > surprising/unpredictable restrictions on migratability.
> > >
> > > Well, alright. If you make the TSC frequency of the host
> > > available to mgmt software as you describe, and write the steps mgmt
> > > software should take, i'm good.
> >
> > I plan to. The problem is that the mechanism to query the host
> > frequency may be unavailable in the first version.
>
> 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?
--
Eduardo
- Re: [Qemu-devel] TSC frequency configuration & invtsc migration (was Re: [PATCH 4/4] kvm: Allow migration with invtsc), (continued)
- Re: [Qemu-devel] TSC frequency configuration & invtsc migration (was Re: [PATCH 4/4] kvm: Allow migration with invtsc), Marcelo Tosatti, 2017/01/05
- Re: [Qemu-devel] 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), 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 <=
- 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, 2017/01/11
- 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