On Tue, Sep 9, 2014 at 11:02 AM, Anup Chenthamarakshan <an...@chromium.org> wrote: > I had initially tried reusing cpufreq_stats.c to export stats. > Calling cpufreq_stats_update() via the cpufreq notifier added > some amount of overhead while switching frequencies. Specifically, > looking up the index of the new frequency in freq_table_get_index() > is a linear search through all available frequencies (vs a single > subtraction with custom stats export). Also, the notifier mechanism
I don't think just this linear search will make things so bad.. > itself added a level of indirection before calling stats_update. Probably some other notifier is registered which is taking considerable amount of time.. Try checking what all registered with cpufreq-core. > There is a 5X increase in time taken to complete intel_pstate_set_pstate > while using cpufreq_stats compared to having custom stats exported. Try calling cpufreq_stat_notifier_trans() directly instead of a notifier and lets see if this makes it any better. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/