RE: [Xen-devel] [PATCH] 1/2: cpufreq/PowerNow! in Xen: Time and platform changes

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

>From: Rik van Riel [mailto:riel@xxxxxxxxxx]
>Sent: 2007年8月31日 2:23
>
>Keir Fraser wrote:
>
>> It's a misleading simplification. For example, the ondemand governor
>will
>> build and run in a dom0 kernel but it's not actually going to do the right
>> thing, as it doesn't observe whole-machine load.
>
>Here is the missing piece of the puzzle.   A platform
>hypercall operation to get system wide idle time.
>
>I believe Mark's changes, together with this little
>patch, are the way we can get cpufreq working on
>Xen with the minimal amount of code duplication.
>
>Duplicating code anywhere, whether it be inside the
>hypervisor or in some Xen-only userland package, will
>only lead to bit rot and make Xen maintenance more
>painful.
>
>Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>
>

The run_state info is not accurate for other vcpus not on current 
processor, since it's only updated when switching out.

Thanks,
Kevin

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