All of lore.kernel.org
 help / color / mirror / Atom feed
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

  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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20160705221226.GR4131@thinpad.lan.raisama.net \
    --to=ehabkost@redhat.com \
    --cc=dmatlack@google.com \
    --cc=haozhong.zhang@intel.com \
    --cc=kvm@vger.kernel.org \
    --cc=mtosatti@redhat.com \
    --cc=pbonzini@redhat.com \
    --cc=peterhornyack@google.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.