From: Eric Blake <eblake@redhat.com>
To: Avi Kivity <avi@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>,
Jan Kiszka <jan.kiszka@siemens.com>,
Michael Roth <mdroth@linux.vnet.ibm.com>,
qemu-devel@nongnu.org, Anthony Liguori <anthony@codemonkey.ws>,
Paolo Bonzini <pbonzini@redhat.com>,
Luiz Capitulino <lcapitulino@redhat.com>
Subject: Re: [Qemu-devel] Rethinking missed tick catchup
Date: Thu, 13 Sep 2012 08:42:19 -0600 [thread overview]
Message-ID: <5051F0CB.9040303@redhat.com> (raw)
In-Reply-To: <5051EF0D.4070109@redhat.com>
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On 09/13/2012 08:34 AM, Avi Kivity wrote:
> On 09/13/2012 05:22 PM, Gleb Natapov wrote:
>>>
>>> It's much easier for us to call into qemu-ga to do the time correction
>>> whenever this event occurs than to try and have libvirt figure out when
>>> it's necessary.
>
>> And if guest does not have qemu-ga what is better inject interrupts like
>> crazy for next 2 minutes or leave guest with incorrect time?
>
> We can try to S3 and resume the guest. The guest will assume that it
> has slept for an unknown amount of time and resync from the RTC.
Just restating to make sure I'm clear: you are proposing that after host
suspend and host wakeup, _then_ qemu asks the guest to go into S3
followed by an immediate resume. During the time that the guest goes
into S3, its clock is way off; but then the immediate resume will be the
necessary kick to the guest to resync, and at that point, the guest can
assume that it has been off since the host originally suspended (rather
than the instant window where qemu actually bounced S3 after the host
had already resumed).
> This may not work for really old server oriented guests.
S3 requires guest cooperation, period. But so does qemu-ga. It's
better than nothing, and we can't get perfection without guest cooperation.
--
Eric Blake eblake@redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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next prev parent reply other threads:[~2012-09-13 14:43 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-12 13:54 [Qemu-devel] Rethinking missed tick catchup Anthony Liguori
2012-09-12 14:21 ` Jan Kiszka
2012-09-12 14:44 ` Anthony Liguori
2012-09-12 14:50 ` Jan Kiszka
2012-09-12 15:06 ` Gleb Natapov
2012-09-12 15:42 ` Jan Kiszka
2012-09-12 15:45 ` Gleb Natapov
2012-09-12 16:16 ` Gleb Natapov
2012-09-12 15:15 ` Gleb Natapov
2012-09-12 18:19 ` Anthony Liguori
2012-09-13 10:49 ` Gleb Natapov
2012-09-13 13:14 ` Eric Blake
2012-09-13 13:28 ` Daniel P. Berrange
2012-09-13 14:06 ` Anthony Liguori
2012-09-13 14:22 ` Gleb Natapov
2012-09-13 14:34 ` Avi Kivity
2012-09-13 14:42 ` Eric Blake [this message]
2012-09-13 15:40 ` Avi Kivity
2012-09-13 15:50 ` Anthony Liguori
2012-09-13 15:53 ` Avi Kivity
2012-09-13 18:27 ` Anthony Liguori
2012-09-16 10:05 ` Avi Kivity
2012-09-16 14:37 ` Anthony Liguori
2012-09-19 15:34 ` Avi Kivity
2012-09-19 16:37 ` Gleb Natapov
2012-09-19 16:44 ` Avi Kivity
2012-09-19 16:55 ` Gleb Natapov
2012-09-19 16:57 ` Avi Kivity
2012-09-13 14:35 ` Anthony Liguori
2012-09-13 14:48 ` Gleb Natapov
2012-09-13 15:51 ` Avi Kivity
2012-09-13 15:56 ` Anthony Liguori
2012-09-13 16:06 ` Gleb Natapov
2012-09-13 18:33 ` Anthony Liguori
2012-09-13 18:56 ` Gleb Natapov
2012-09-13 20:06 ` Anthony Liguori
2012-09-13 16:08 ` Avi Kivity
2012-09-13 13:47 ` Gleb Natapov
2012-09-12 16:27 ` Stefan Weil
2012-09-12 16:45 ` Gleb Natapov
2012-09-12 17:30 ` Stefan Weil
2012-09-12 18:13 ` Gleb Natapov
2012-09-12 19:45 ` Stefan Weil
2012-09-13 10:50 ` Gleb Natapov
2012-09-12 20:06 ` Michael Roth
2012-09-12 17:23 ` Luiz Capitulino
-- strict thread matches above, loose matches on Subject: below --
2012-09-12 18:03 Clemens Kolbitsch
2012-09-13 6:25 ` Paolo Bonzini
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