From: Paolo Bonzini <pbonzini@redhat.com>
To: Eduardo Habkost <ehabkost@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>
Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org,
Haozhong Zhang <haozhong.zhang@intel.com>,
libvir-list@redhat.com
Subject: Re: Exporting kvm_max_guest_tsc_khz to userspace (was Re: [PATCH 4/4] kvm: Allow migration with invtsc)
Date: Mon, 9 Jan 2017 15:58:11 +0100 [thread overview]
Message-ID: <d9ff1970-7d2d-6a49-b93e-27fe2817f412@redhat.com> (raw)
In-Reply-To: <20170108202851.GZ3315@thinpad.lan.raisama.net>
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.
Paolo
WARNING: multiple messages have this Message-ID (diff)
From: Paolo Bonzini <pbonzini@redhat.com>
To: Eduardo Habkost <ehabkost@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>
Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org,
Haozhong Zhang <haozhong.zhang@intel.com>,
libvir-list@redhat.com
Subject: Re: [Qemu-devel] Exporting kvm_max_guest_tsc_khz to userspace (was Re: [PATCH 4/4] kvm: Allow migration with invtsc)
Date: Mon, 9 Jan 2017 15:58:11 +0100 [thread overview]
Message-ID: <d9ff1970-7d2d-6a49-b93e-27fe2817f412@redhat.com> (raw)
In-Reply-To: <20170108202851.GZ3315@thinpad.lan.raisama.net>
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.
Paolo
next prev parent reply other threads:[~2017-01-09 14:58 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-27 19:21 [PATCH 0/4] Allow migration with invtsc if there's no frequency mismatch Eduardo Habkost
2016-12-27 19:21 ` [Qemu-devel] " Eduardo Habkost
2016-12-27 19:21 ` [PATCH 1/4] kvm: Simplify invtsc check Eduardo Habkost
2016-12-27 19:21 ` [Qemu-devel] " Eduardo Habkost
2016-12-29 18:57 ` Marcelo Tosatti
2016-12-29 18:57 ` [Qemu-devel] " Marcelo Tosatti
2016-12-27 19:21 ` [PATCH 2/4] kvm: Allow invtsc migration if tsc-khz is set explicitly Eduardo Habkost
2016-12-27 19:21 ` [Qemu-devel] " Eduardo Habkost
2017-01-04 11:44 ` Marcelo Tosatti
2017-01-04 11:44 ` [Qemu-devel] " Marcelo Tosatti
2017-01-04 11:57 ` Marcelo Tosatti
2017-01-04 11:57 ` [Qemu-devel] " Marcelo Tosatti
2017-01-04 13:40 ` Eduardo Habkost
2017-01-04 13:40 ` [Qemu-devel] " Eduardo Habkost
2017-01-04 13:45 ` Marcelo Tosatti
2017-01-04 13:45 ` [Qemu-devel] " Marcelo Tosatti
2017-01-04 13:51 ` Eduardo Habkost
2017-01-04 13:51 ` [Qemu-devel] " Eduardo Habkost
2016-12-27 19:21 ` [PATCH 3/4] pc: Add 2.9 machine-types Eduardo Habkost
2016-12-27 19:21 ` [Qemu-devel] " Eduardo Habkost
2016-12-30 13:38 ` Igor Mammedov
2016-12-30 13:38 ` [Qemu-devel] " Igor Mammedov
2017-01-04 14:01 ` Laszlo Ersek
2017-01-04 14:20 ` Eduardo Habkost
2017-01-04 14:20 ` [Qemu-devel] " Eduardo Habkost
2017-01-04 16:40 ` Laszlo Ersek
2017-01-04 16:40 ` [Qemu-devel] " Laszlo Ersek
2017-01-04 17:46 ` Eduardo Habkost
2016-12-27 19:21 ` [PATCH 4/4] kvm: Allow migration with invtsc Eduardo Habkost
2016-12-27 19:21 ` [Qemu-devel] " Eduardo Habkost
2017-01-04 11:56 ` Marcelo Tosatti
2017-01-04 11:56 ` [Qemu-devel] " Marcelo Tosatti
2017-01-04 13:39 ` Eduardo Habkost
2017-01-04 13:39 ` [Qemu-devel] " Eduardo Habkost
2017-01-04 19:59 ` [libvirt] TSC frequency configuration & invtsc migration (was Re: [PATCH 4/4] kvm: Allow migration with invtsc) Eduardo Habkost
2017-01-04 19:59 ` [Qemu-devel] " Eduardo Habkost
2017-01-04 22:26 ` Marcelo Tosatti
2017-01-04 22:26 ` [Qemu-devel] " Marcelo Tosatti
2017-01-05 1:36 ` Eduardo Habkost
2017-01-05 1:36 ` [Qemu-devel] " Eduardo Habkost
2017-01-05 10:48 ` Marcelo Tosatti
2017-01-05 10:48 ` [Qemu-devel] " Marcelo Tosatti
2017-01-05 10:50 ` Marcelo Tosatti
2017-01-05 10:50 ` [Qemu-devel] " Marcelo Tosatti
2017-01-05 12:19 ` Eduardo Habkost
2017-01-05 12:19 ` [Qemu-devel] " Eduardo Habkost
2017-01-05 12:33 ` [libvirt] " Daniel P. Berrange
2017-01-05 12:33 ` [Qemu-devel] " Daniel P. Berrange
2017-01-05 12:48 ` Eduardo Habkost
2017-01-05 12:48 ` [Qemu-devel] " Eduardo Habkost
2017-01-05 13:00 ` Daniel P. Berrange
2017-01-05 13:00 ` [Qemu-devel] " Daniel P. Berrange
2017-01-05 13:11 ` Eduardo Habkost
2017-01-05 13:11 ` [Qemu-devel] " Eduardo Habkost
2017-01-10 16:38 ` Paolo Bonzini
2017-01-10 16:38 ` [Qemu-devel] " Paolo Bonzini
2017-01-06 10:31 ` Marcelo Tosatti
2017-01-06 10:31 ` [Qemu-devel] " Marcelo Tosatti
2017-01-08 15:49 ` How to make dest host abort migration safely " Eduardo Habkost
2017-01-08 15:49 ` [Qemu-devel] " Eduardo Habkost
2017-01-09 10:04 ` [libvirt] " Dr. David Alan Gilbert
2017-01-09 10:04 ` [Qemu-devel] " Dr. David Alan Gilbert
2017-01-08 20:28 ` Exporting kvm_max_guest_tsc_khz to userspace " Eduardo Habkost
2017-01-08 20:28 ` [Qemu-devel] " Eduardo Habkost
2017-01-09 14:58 ` Paolo Bonzini [this message]
2017-01-09 14:58 ` Paolo Bonzini
2017-01-11 13:26 ` Eduardo Habkost
2017-01-11 13:26 ` [Qemu-devel] " Eduardo Habkost
2017-01-11 14:06 ` Paolo Bonzini
2017-01-11 14:06 ` [Qemu-devel] " Paolo Bonzini
2017-01-10 16:36 ` TSC frequency configuration & invtsc migration " Paolo Bonzini
2017-01-10 16:36 ` [Qemu-devel] " Paolo Bonzini
2017-01-11 11:58 ` Eduardo Habkost
2017-01-11 11:58 ` [Qemu-devel] " Eduardo Habkost
2017-01-18 11:55 ` Marcelo Tosatti
2017-01-18 11:55 ` [Qemu-devel] " Marcelo Tosatti
2017-01-18 12:43 ` Eduardo Habkost
2017-01-18 12:43 ` [Qemu-devel] " Eduardo Habkost
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