Re: [PATCH 04/17] Fix deep C-state TSC desynchronization

Zachary Amsden
2010-06-16T19:20:30Z

On 06/16/2010 03:24 AM, Glauber Costa wrote:
> On Mon, Jun 14, 2010 at 09:34:06PM -1000, Zachary Amsden wrote:
>
>> When CPUs with unstable TSCs enter deep C-state, TSC may stop
>> running. This causes us to require resynchronization. Since
>> we can't tell when this may potentially happen, we assume the
>> worst by forcing re-compensation for it at every point the VCPU
>> task is descheduled.
>>
> can't we just compensate everytime check_tsc_unstable() is true?
>

We should probably not rely on check_tsc_unstable, we should do this
only if we don't have NONSTOP_TSC.