On Sunday, 20 of January 2008, Tomasz Chmielewski wrote: > >> Clock throttling is not likely to save your battery, unless you have > >> tasks that are running at 100% CPU for an unlimited time or something, > >> and you force your CPU to throttle. Normally most people have tasks that > >> run and then the CPU idles - loading an email, displaying a web page, > >> etc. Clock throttling will just make these tasks utilize the CPU for a > >> longer time proportional to the amount clock throttling and therefore > >> negate any gains in battery usage. > > Aren't you forgetting about CPUfreq governors? Which mean: use the > maximum CPU frequency when the system is busy, throttle down (or lower > voltage) when the system is idle. > > So yes, throttling will save the battery.
In the relevant documentation "throttling" usually means "the reduction of the frequency of a CPU that is not idle" in which case it won't (at least on the average). > Besides, not all CPUs support power management (voltage control). > > > > IMO clock throttling (as opposed to the reduction of the frequency of an > > idle > > CPU) is only useful for preventing the CPU from overheating. > > And for reducing power on CPUs that can't do any power management, just > throttling. > > For example, a server that doesn't crunch any numbers at night will > certainly use less power when throttled. You can't use less power, you only can use less energy. :-) Anyway, that's "the reduction of the frequency of an idle CPU" mentioned above and it makes sense in the majority of cases. Greetings, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
