From: Eduardo Habkost <ehabkost@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>,
David Matlack <dmatlack@google.com>,
Peter Hornyack <peterhornyack@google.com>,
KVM list <kvm@vger.kernel.org>,
haozhong.zhang@intel.com
Subject: Re: TSC deadline timer in guests vs. migration?
Date: Tue, 5 Jul 2016 19:12:26 -0300 [thread overview]
Message-ID: <20160705221226.GR4131@thinpad.lan.raisama.net> (raw)
In-Reply-To: <4ff33059-2f46-5767-4b59-82780cf01483@redhat.com>
On Tue, Jul 05, 2016 at 11:40:22PM +0200, Paolo Bonzini wrote:
>
>
> On 05/07/2016 20:11, Eduardo Habkost wrote:
> > In this case, if TSC scaling is not supported, is it preferable
> > to have the TSC frequency suddenly changing without the guest
> > being aware of it, or to run in tsc_always_catchup mode? QEMU 2.5
> > did the former, QEMU 2.6 does the latter.
>
> I suspect the former is better just because we don't know the exact
> effect of tsc_always_catchup.
Forget what I said. QEMU 2.6 checks for KVM_CAP_TSC_CONTROL
before calling KVM_SET_TSC_KHZ. In this case, it will never
trigger tsc_always_catchup, right?
--
Eduardo
next prev parent reply other threads:[~2016-07-05 22:12 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-04 11:01 TSC deadline timer in guests vs. migration? Paolo Bonzini
2016-07-04 19:07 ` Eduardo Habkost
2016-07-05 10:48 ` Paolo Bonzini
2016-07-04 19:30 ` Marcelo Tosatti
2016-07-04 19:45 ` Eduardo Habkost
2016-07-04 20:17 ` Paolo Bonzini
2016-07-05 12:51 ` Marcelo Tosatti
2016-07-05 13:04 ` Eduardo Habkost
2016-07-05 13:34 ` Paolo Bonzini
2016-07-05 18:11 ` Eduardo Habkost
2016-07-05 21:40 ` Paolo Bonzini
2016-07-05 22:12 ` Eduardo Habkost [this message]
2016-07-06 6:01 ` Paolo Bonzini
2016-07-05 20:39 ` Marcelo Tosatti
2016-07-05 21:41 ` Paolo Bonzini
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