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Re: [RFC/RFT][PATCH v3 2/2] cpufreq: schedutil: Switching frequencies from interrupt context

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On Thursday, February 25, 2016 10:12:49 AM Peter Zijlstra wrote:
> On Thu, Feb 25, 2016 at 10:08:40AM +0100, Peter Zijlstra wrote:
> > On Thu, Feb 25, 2016 at 12:30:43AM +0100, Rafael J. Wysocki wrote:
> > > +unsigned int acpi_cpufreq_fast_switch(struct cpufreq_policy *policy,
> > > +				      unsigned int target_freq)
> > > +{
> > > +	struct acpi_cpufreq_data *data = policy->driver_data;
> > > +	struct cpufreq_frequency_table *entry;
> > > +	struct acpi_processor_performance *perf;
> > > +	unsigned int uninitialized_var(next_perf_state);
> > > +	unsigned int uninitialized_var(next_freq);
> > > +	unsigned int best_diff;
> > > +
> > > +	for (entry = data->freq_table, best_diff = UINT_MAX;
> > > +	     entry->frequency != CPUFREQ_TABLE_END; entry++) {
> > > +		unsigned int diff, freq = entry->frequency;
> > > +
> > > +		if (freq == CPUFREQ_ENTRY_INVALID)
> > > +			continue;
> > > +
> > > +		diff = abs(freq - target_freq);
> > 
> > Why would you consider frequencies that are below where you want to be?
> 
> Also, if you look for the first largest freq (which would make most
> sense I think) and this table is sorted, you can do a binary search.
> 
> Then again, not sure the table is big enough to make that worth it.

Yeah, that was my thought too.

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[RFC/RFT][PATCH v2 0/2] cpufreq: New governor based on scheduler-provided utilization data "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-24 02:30 +0100
  [RFC/RFT][PATCH v2 1/2] cpufreq: New governor using utilization data from the scheduler "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-24 02:30 +0100
    [RFC/RFT][PATCH v4 1/2] cpufreq: New governor using utilization data from the scheduler "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-25 22:20 +0100
      Re: [RFC/RFT][PATCH v4 1/2] cpufreq: New governor using utilization data from the scheduler "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-27 01:30 +0100
      Re: [RFC/RFT][PATCH v4 1/2] cpufreq: New governor using utilization  data from the scheduler Steve Muckle <steve.muckle@linaro.org> - 2016-02-27 05:40 +0100
        Re: [RFC/RFT][PATCH v4 1/2] cpufreq: New governor using utilization data from the scheduler "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-27 16:30 +0100
          Re: [RFC/RFT][PATCH v4 1/2] cpufreq: New governor using utilization  data from the scheduler Steve Muckle <steve.muckle@linaro.org> - 2016-03-01 05:20 +0100
            Re: [RFC/RFT][PATCH v4 1/2] cpufreq: New governor using utilization  data from the scheduler "Rafael J. Wysocki" <rafael@kernel.org> - 2016-03-01 21:30 +0100
              Re: [RFC/RFT][PATCH v4 1/2] cpufreq: New governor using utilization  data from the scheduler Steve Muckle <steve.muckle@linaro.org> - 2016-03-03 04:30 +0100
                Re: [RFC/RFT][PATCH v4 1/2] cpufreq: New governor using utilization  data from the scheduler Steve Muckle <steve.muckle@linaro.org> - 2016-03-03 04:40 +0100
                Re: [RFC/RFT][PATCH v4 1/2] cpufreq: New governor using utilization  data from the scheduler "Rafael J. Wysocki" <rafael@kernel.org> - 2016-03-03 20:30 +0100
  [RFC/RFT][PATCH v2 2/2] cpufreq: schedutil: Switching frequencies from interrupt context "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-24 02:30 +0100
    [RFC/RFT][PATCH v3 2/2] cpufreq: schedutil: Switching frequencies from interrupt context "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-25 00:30 +0100
      Re: [RFC/RFT][PATCH v3 2/2] cpufreq: schedutil: Switching  frequencies from interrupt context Peter Zijlstra <peterz@infradead.org> - 2016-02-25 10:10 +0100
        Re: [RFC/RFT][PATCH v3 2/2] cpufreq: schedutil: Switching  frequencies from interrupt context Peter Zijlstra <peterz@infradead.org> - 2016-02-25 10:20 +0100
          Re: [RFC/RFT][PATCH v3 2/2] cpufreq: schedutil: Switching frequencies from interrupt context "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-25 12:20 +0100
        Re: [RFC/RFT][PATCH v3 2/2] cpufreq: schedutil: Switching frequencies from interrupt context "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-25 12:10 +0100
          Re: [RFC/RFT][PATCH v3 2/2] cpufreq: schedutil: Switching  frequencies from interrupt context Peter Zijlstra <peterz@infradead.org> - 2016-02-25 13:00 +0100
            Re: [RFC/RFT][PATCH v3 2/2] cpufreq: schedutil: Switching frequencies from interrupt context "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-25 22:00 +0100
    [RFC/RFT][PATCH v4 2/2] cpufreq: schedutil: Switching frequencies from interrupt context "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-25 22:20 +0100

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