On Sat, Jun 14, 2008 at 3:54 AM, Eric Saxe <Eric.Saxe at sun.com> wrote: > Bill Holler wrote: >> >> PAD data will be a huge hint to the idle thread for which c-state >> it can enter. We have several models to try. :-) Here is what >> we are planning: >> >> CPUs in low power group will always attempts to enter the >> deepest c-state possible with a latency some multiple less than >> the time till the next cyclic. Idle threads will keep track of >> its success rate in entering the deeper c-states. We do not yet >> know if success-rate data needs to be used in the low-power- >> processor-group c-state policy. >> CPUs in the higher power groups have a larger chance a thread >> will be dispatched on them before the next cyclic expires. >> We are not sure yet how to model this prediction. Success >> data will probably be very important here. > We might also experiment with tracking the "depth of sleep" for a CPU, > and given all else is equal have the dispatcher prefer CPUs in a > shallower sleep. > So we'll have two power groups? What determines which CPU is in which group?
Thanks, -Aubrey
