On Mon, 19 Apr 2010 10:09:55 +0100 Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxx> wrote: > Is the improvement really because IO benefited from CPU being held at > a higher frequency, or perhaps because it is now not scaled down > during IO, so when CPU intensive part of git grep comes along it is > already "revved up"? the IO part does not get much faster (some systems lower the FSB speed at low frequencies, but disks are still much slower than the FSB anyway), but the CPU part, which is performance critical for, say, "git grep" does go faster. > > Or in other words, does a pure IO workload benefit from now higher > selected frequency? no. Mixed workloads do. but pure IO workloads also don't suffer since while idle, the voltage goes down anyway. > > One idea I had but a) never had time to implement it and b) was not > sure it would be accepted anyway, was to modify ondemand governor to > ramp up instantly, but slow down slowly (in a configurable way). that's what ondemand does already. -- Arjan van de Ven Intel Open Source Technology Centre For development, discussion and tips for power savings, visit http://www.lesswatts.org -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
