> > So from what I can see, it appears that C3 is always available, but > there are some circumstances where the idle logic can't figure out that > it can get there. If I can change the circumstances, in this case by > using the native console, those circumstances change and it idles to C3.
there's a few things about C3 that are relevant: * if you're too short in C3 (less than say 1 to 5 msec, depending on the cpu model), you actually waste more power in the transition compared to just being in C2 * During C3, the CPU disables bus snooping; once DMA happens the CPU has to wake up again. If you have high frequency DMA going on, it's better to stay in C2 for the same reason as above _______________________________________________ Power mailing list [email protected] http://www.bughost.org/mailman/listinfo/power
