James wrote: > Hi, > > I've noticed something with my system (kernel 2.6.25.11) that seems odd. > If I understood > the docs on the web page, the cpufreq governor should be doing > "race-to-idle": running at > full speed so as to get to idle faster. However, the processor's a Core2 > Duo at 2.2 GHz, > but /proc/cpuinfo says it's running at 800 MHz, and powertop says it's > spending its running > time in an 800 MHz P-state. > > Have I missed something? > > Thanks, > James > > _______________________________________________ > Discuss mailing list > [email protected] > http://mail.lesswatts.org/mailman/listinfo/discuss > It actually depends on which governor you're using.
If you're running with the ondemand governor, the system's P-State will be controlled by the amount of idle time in the system. Running top will show you the amount of time that the system is idle. If there is is idle time in the system, then ondemand will start using the lower P-States, but as soon as it detects there is a task that wants the CPU, it will bounce it up to the maximum P-State. The Core2 duo makes it a little more complicated, in that the lower P-States cannot be entered unless both cores are happy to go down, and cpufreq/ondemand handle the cores separately. So if one core is busy, and the other is idle, both cores will be in the highest P-State. If you are in fact using the ondemand governor, then the system should be running under the 'race-to-halt' policy. There is documentation in the linux kernel source which describes the exact operation of all the different governors that cpufreq provides. Regards, Etienne Le Sueur _______________________________________________ Discuss mailing list [email protected] http://mail.lesswatts.org/mailman/listinfo/discuss
