RE: [Xen-devel] [PATCH][cpufreq] Xen support for the ondemand governor [1/2] (hypervisor code)

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

>From: Mark Langsdorf
>Sent: 2007年10月24日 6:00
>
>Modify the cpufreq ondemand governor so that it can get idle and
>total ticks from the Xen hypervisor.  Linux and Xen have different
>ideas of what an idle tick is, so the Xen values for both have to
>be returned in the same platform hypercall.
>
>Signed-off-by: Mark Langsdorf <mark.langsdorf@xxxxxxx>

I would suggest adding bit mask info into getidletime, and then only 
fetching idle stats of concerned cpus. Currently [0-max_cpus] is 
overkill when on-demand governor only takes care of one cpu (hw 
coordination) or sibling cores (sw coordination).

Also there's no need to return total time for each concerned cpu. For 
sw coordination model, on-demand governor only runs on one cpu 
and getidletime is only called on that agent cpu which takes care of 
all the rest idle stats. Naturally elapsed cycles since last sample point 
should be same on all affected cpus and it's useless to cal for them 
individually. You just need to stamp NOW() for the sample point.

Thanks,
Kevin

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