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

    > + if (diff >= best_diff)
    > + continue;
    > +
    > + best_diff = diff;
    > + next_perf_state = entry->driver_data;
    > + next_freq = freq;
    > + if (best_diff == 0)
    > + goto found;
    > + }
    > + if (best_diff == UINT_MAX)
    > + return CPUFREQ_ENTRY_INVALID;
    > +
    > + found:
    > + perf = to_perf_data(data);
    > + if (perf->state == next_perf_state) {
    > + if (unlikely(data->resume))
    > + data->resume = 0;
    > + else
    > + return next_freq;
    > + }
    > +
    > + data->cpu_freq_fast_write(perf->states[next_perf_state].control);
    > + perf->state = next_perf_state;
    > + return next_freq;
    > +}

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