Re: [PATCH] cpufreq: intel_pstate: Change the calculation of next pstate

[Dirk Brandewie]

On 04/29/2014 02:52 PM, Rafael J. Wysocki wrote:
> On Tuesday, April 29, 2014 07:34:46 PM Stratos Karafotis wrote:
> > On 29/04/2014 07:58 ÏÎ, Viresh Kumar wrote:
> > > Cc'd Dirk,
> > >
> > > On 28 April 2014 03:42, Stratos Karafotis <stratosk@xxxxxxxxxxxx> wrote:
> > > > Currently the driver calculates the next pstate proportional to
> > > > core_busy factor and reverse proportional to current pstate.
> > > >
> > > > Change the above method and calculate the next pstate independently
> > > > of current pstate.
> > >
> > > We must mention why the change is required.
> >
> > Hi Viresh,
> >
> > Actually, I can't say that it's required. :)
> > I just believe that calculation of next p-state should be independent
> > from current one. In my opinion we can't scale the load across different
> > p-states, because it's not always equivalent.
> >
> > For example suppose a load of 100% because of a tight for loop in the
> > current p-state. It will be also a 100% load in any other p-state.
> > It will be wrong if we scale the load in the calculation formula
> > according to the current p-state.
> >
> > I included the test results in the change log to point out an improvement
> > because of this patch.
> >
> > I will enrich more the change log as you suggested.
>
> Please do so.
>
> Also, we need to take your patch to our power lab and see if we can reproduce
> your results in other workloads.
>
> And I'm waiting for the intel_pstate developer Dirk Brandewie to comment.

Sorry I just returned from dealing with a family emergency and am digging
out of my inbox.

I will run this patch through some tests.


> Thanks!

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