Hello, 2011/7/3 Rafael J. Wysocki <rjw@xxxxxxx>: > Hi, > > On Friday, May 27, 2011, MyungJoo Ham wrote: >> Three CPUFREQ-like governors are provided as examples. >> >> powersave: use the lowest frequency possible. The user (device) should >> set the polling_ms as 0 because polling is useless for this governor. >> >> performance: use the highest freqeuncy possible. The user (device) >> should set the polling_ms as 0 because polling is useless for this >> governor. >> >> simple_ondemand: simplified version of CPUFREQ's ONDEMAND governor. >> >> When a user updates OPP entries (enable/disable/add), OPP framework >> automatically notifies DEVFREQ to update operating frequency >> accordingly. Thus, DEVFREQ users (device drivers) do not need to update >> DEVFREQ manually with OPP entry updates or set polling_ms for powersave >> , performance, or any other "static" governors. >> >> Signed-off-by: MyungJoo Ham <myungjoo.ham@xxxxxxxxxxx> >> Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx> [] >> + >> + /* Set the desired frequency based on the load */ >> + a = (unsigned long long) stat.busy_time * stat.current_frequency; > > What's the purpose of the conversion? Assuming that the work speed of a device is proportional to its frequency, it measures the amount of work done. It's time * work/time. For example, during the last 10 second, if the busy_time was 5 sec and frequency was 10MHz, it's "50M", which is same as 20MHz and 2.5 sec. > >> + b = div_u64(a, stat.total_time); >> + b *= 100; >> + b = div_u64(b, (DFSO_UPTHRESHOLD - DFSO_DOWNDIFFERENCTIAL / 2)); >> + *freq = (unsigned long) b; >> + >> + return 0; >> +} > > Rafael > -- MyungJoo Ham (함명주), Ph.D. Mobile Software Platform Lab, Digital Media and Communications (DMC) Business Samsung Electronics cell: 82-10-6714-2858 _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
