On Saturday 16 February 2008 00:27, John McCabe-Dansted wrote: > After reading > http://www.bughost.org/pipermail/power/2007-May/000166.html > I've filed a bug about Ubuntu's use of ignore_nice_load: > https://bugs.launchpad.net/ubuntu/+source/sysvinit/+bug/192303 > > I understand that due to the "Race to idle", it would actually save > power to run nice tasks at full speed. Thus, except in edge cases, > such as when the nice task caught in a loop, the ignore_nice_load > option is pointless. > > Would you agree that ignore_nice_load should not be set by default?
Venki should probably speak to ignore_nice_load. > Secondly, as setting the CPU frequency saves little power during idle, > why do you recommend ondemand rather than performance? There are many different types of systems. Some have a highly optimized idle that saves non-linear power and rewards race-to-idle. Some do not. Some save more power in idle when entered at a lower "frequency". (Actually it is the voltage associated w/ the frequency that helps). Others lower the voltage on entering idle automatically, and thus don't care what P-state they were in when they went idle. Some systems consume a non-linear amount of additinal power when running at maximum frequencey, and thus race to idle isn't necessarily always an energy savings. > Also what up_threshold do you recommend? (Ubuntu uses 31% by default, > but AFAICT, race to idle would mean that a lower up_threshold would > actually save power) > > Finally, are there older CPUs for which the "conservative" governor > would make sense? AFAIK, conservative is not useful on any Intel processors. I've heard that it is well suited for some older AMD processors, but I don't know first hand. We've totally ignored the conservative governor for all of our tuning on Intel processors. Davej threatened to delete conservative last year and make it a mode for ondemand instead, but that hasn't happened yet. cheers, -Len > If so, could you tell me off the top of your head which ones they are? > > With thanks, > _______________________________________________ Power mailing list [email protected] http://www.bughost.org/mailman/listinfo/power
