From: Zachary Amsden <zamsden@redhat.com>
To: Jan Kiszka <jan.kiszka@web.de>
Cc: Glauber Costa <glommer@redhat.com>,
kvm@vger.kernel.org, Avi Kivity <avi@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
John Stultz <johnstul@us.ibm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [KVM timekeeping 10/35] Fix deep C-state TSC desynchronization
Date: Fri, 17 Sep 2010 12:31:08 -1000 [thread overview]
Message-ID: <4C93EC2C.1000402@redhat.com> (raw)
In-Reply-To: <4C93E734.4040208@redhat.com>
On 09/17/2010 12:09 PM, Zachary Amsden wrote:
> On 09/15/2010 08:27 AM, Jan Kiszka wrote:
>> Am 15.09.2010 14:32, Glauber Costa wrote:
>>> On Wed, Sep 15, 2010 at 10:09:33AM +0200, Jan Kiszka wrote:
>>>>> In any case, I'll proceed with the forcing of unstable TSC and HPET
>>>>> clocksource and see what happens.
>>>> I tried that before, but it did not trigger the issue that kvm-clock
>>>> guests no longer boot properly. This only happens if the TSC is marked
>>>> unstable.
>>> even artificially marked unstable ?
>>>
>> Yes. As soon as I hack tsc_unstable to 1, things go wrong. When I hack
>> it back to 0, guest that wants kvm-clock boots again and seem to run
>> fine.
>>
>> This is issue #2, I guess. Issue #2 remains that the TSC is marked
>> unstable. I have the feeling that this is bogus, maybe due to lacking
>> suspend/resume awareness? The tsc clocksource does
>>
>> clocksource_tsc.cycle_last = 0;
>>
>> on resume...
>>
>> Jan
>>
>
> I have now reproduced this exactly. Shouldn't be long before I have a
> solution.
Actually, here is what I am seeing: the guest proceeds - in SUPER SLOW
MO... the effect of this patch negates time when the guest is not
running. If the guest is not running because it is idle, negating time
is the wrong thing to do. Left to sit, the boot process still proceeds,
but it goes so slow, you can grow a beard in that time.
Instead, we need wallclock awareness to be preserved. Should be easy to
work in one of my later patches which does this.
Zach
next prev parent reply other threads:[~2010-09-17 22:31 UTC|newest]
Thread overview: 106+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-20 8:07 KVM timekeeping and TSC virtualization Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 01/35] Drop vm_init_tsc Zachary Amsden
2010-08-20 16:54 ` Glauber Costa
2010-08-20 8:07 ` [KVM timekeeping 02/35] Convert TSC writes to TSC offset writes Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 03/35] Move TSC offset writes to common code Zachary Amsden
2010-08-20 17:06 ` Glauber Costa
2010-08-24 0:51 ` Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 04/35] Fix SVM VMCB reset Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 05/35] Move TSC reset out of vmcb_init Zachary Amsden
2010-08-20 17:08 ` Glauber Costa
2010-08-24 0:52 ` Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 06/35] TSC reset compensation Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 07/35] Make cpu_tsc_khz updates use local CPU Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 08/35] Warn about unstable TSC Zachary Amsden
2010-08-20 17:28 ` Glauber Costa
2010-08-24 0:56 ` Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 09/35] Unify TSC logic Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 10/35] Fix deep C-state TSC desynchronization Zachary Amsden
2010-08-20 17:30 ` Glauber Costa
2010-09-14 9:10 ` Jan Kiszka
2010-09-14 9:27 ` Avi Kivity
2010-09-14 10:40 ` Jan Kiszka
2010-09-14 10:47 ` Avi Kivity
2010-09-14 19:32 ` Zachary Amsden
2010-09-14 22:26 ` Jan Kiszka
2010-09-14 23:40 ` Zachary Amsden
2010-09-15 5:34 ` Jan Kiszka
2010-09-15 7:55 ` Avi Kivity
2010-09-15 8:04 ` Jan Kiszka
2010-09-15 12:29 ` Glauber Costa
2010-09-15 4:07 ` Zachary Amsden
2010-09-15 8:09 ` Jan Kiszka
2010-09-15 12:32 ` Glauber Costa
2010-09-15 18:27 ` Jan Kiszka
2010-09-17 22:09 ` Zachary Amsden
2010-09-17 22:31 ` Zachary Amsden [this message]
2010-09-18 23:53 ` Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 11/35] Add helper functions for time computation Zachary Amsden
2010-08-20 17:34 ` Glauber Costa
2010-08-24 0:58 ` Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 12/35] Robust TSC compensation Zachary Amsden
2010-08-20 17:40 ` Glauber Costa
2010-08-24 1:01 ` Zachary Amsden
2010-08-24 21:33 ` Daniel Verkamp
2010-08-20 8:07 ` [KVM timekeeping 13/35] Perform hardware_enable in CPU_STARTING callback Zachary Amsden
2010-08-27 16:32 ` Jan Kiszka
2010-08-27 23:43 ` Zachary Amsden
2010-08-30 9:10 ` Jan Kiszka
2010-08-20 8:07 ` [KVM timekeeping 14/35] Add clock sync request to hardware enable Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 15/35] Move scale_delta into common header Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 16/35] Fix a possible backwards warp of kvmclock Zachary Amsden
2011-09-02 18:34 ` Philipp Hahn
2011-09-05 14:06 ` [BUG, PATCH-2.6.32] " Philipp Hahn
2011-09-12 11:32 ` Marcelo Tosatti
2010-08-20 8:07 ` [KVM timekeeping 17/35] Implement getnsboottime kernel API Zachary Amsden
2010-08-20 18:39 ` john stultz
2010-08-20 23:37 ` Zachary Amsden
2010-08-21 0:02 ` john stultz
2010-08-21 0:52 ` Zachary Amsden
2010-08-21 1:04 ` john stultz
2010-08-21 1:22 ` Zachary Amsden
2010-08-27 18:05 ` Jan Kiszka
2010-08-27 23:48 ` Zachary Amsden
2010-08-30 18:07 ` Jan Kiszka
2010-08-20 8:07 ` [KVM timekeeping 18/35] Use getnsboottime in KVM Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 19/35] Add timekeeping documentation Zachary Amsden
2010-08-20 17:50 ` Glauber Costa
2010-08-20 8:07 ` [KVM timekeeping 20/35] Make math work for other scales Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 21/35] Track max tsc_khz Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 22/35] Track tsc last write in vcpu Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 23/35] Set initial TSC rate conversion factors Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 24/35] Timer request function renaming Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 25/35] Add clock catchup mode Zachary Amsden
2010-08-25 17:27 ` Marcelo Tosatti
2010-08-25 20:48 ` Zachary Amsden
2010-08-25 22:01 ` Marcelo Tosatti
2010-08-25 23:38 ` Glauber Costa
2010-08-26 0:17 ` Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 26/35] Catchup slower TSC to guest rate Zachary Amsden
2010-09-07 3:44 ` Dong, Eddie
2010-09-07 22:14 ` Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 27/35] Add TSC trapping Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 28/35] Unstable TSC write compensation Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 29/35] TSC overrun protection Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 30/35] IOCTL for setting TSC rate Zachary Amsden
2010-08-20 17:56 ` Glauber Costa
2010-08-21 16:11 ` Arnd Bergmann
2010-08-20 8:07 ` [KVM timekeeping 31/35] Exit conditions for TSC trapping Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 32/35] Entry " Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 33/35] Indicate reliable TSC in kvmclock Zachary Amsden
2010-08-20 17:45 ` Glauber Costa
2010-08-24 1:14 ` Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 34/35] Remove dead code Zachary Amsden
2010-08-20 8:07 ` [KVM timekeeping 35/35] Add some debug stuff Zachary Amsden
2010-08-20 13:26 ` KVM timekeeping and TSC virtualization David S. Ahern
2010-08-20 23:24 ` Zachary Amsden
2010-08-22 1:32 ` David S. Ahern
2010-08-24 1:44 ` Zachary Amsden
2010-08-24 3:04 ` David S. Ahern
2010-08-24 5:47 ` Zachary Amsden
2010-08-24 13:32 ` David S. Ahern
2010-08-24 23:01 ` Zachary Amsden
2010-08-25 16:55 ` Marcelo Tosatti
2010-08-25 20:32 ` Zachary Amsden
2010-08-24 22:13 ` Marcelo Tosatti
2010-08-25 4:04 ` Zachary Amsden
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