* Henrique de Moraes Holschuh (hmh@xxxxxxxxxx) wrote: > On Fri, 24 Apr 2009, Mathieu Desnoyers wrote: > > * Len Brown (lenb@xxxxxxxxxx) wrote: > > > Somebody please remind me why we are spending effort to > > > maintain the conservative governor instead of deleting it. > > > > Documentation/cpu-freq/governors.txt > > > > "The CPUfreq governor "conservative", much like the "ondemand" > > governor, sets the CPU depending on the current usage. It differs in > > behaviour in that it gracefully increases and decreases the CPU speed > > rather than jumping to max speed the moment there is any load on the > > CPU. This behaviour more suitable in a battery powered environment." > > > > So better battery usage seems to be the reason why conservative lives. > > Yeah, but the question is: is it really better in practice? race-to-idle > works better with ondemand. Note: that needs to be answered not just for > the current crop of mobile processors, but also for at least stuff as old as > the Pentium M and Pentium 4 M. > > What it _does_ help, is in broken !@#$ hardware that makes a lot of noise > due to "singing capacitors" if you use ondemand (because conservative will > make less noise as it causes more smooth transitions). NOHZ helped a great > deal there, too. > I effectively have such singing capacitors on my laptop, and I still have good ears. > I don't know if there are battery environments where a harsher work profile > by the CPU are a bad idea. If there are any, conservative will also help > there. > Good question. We might also consider that anyway code duplication between ondemand and conservative is a bad thing. Those look so similar that part of them should probably be merged, with a sysfs flag and kernel parameter to select the behavior. Mathieu > -- > "One disk to rule them all, One disk to find them. One disk to bring > them all and in the darkness grind them. In the Land of Redmond > where the shadows lie." -- The Silicon Valley Tarot > Henrique Holschuh -- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 -- 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
