cpuidle: midterm report
With the good preparation in quarter term/bonding period, I have completed the generic cpuidle kernel module, native intel cpuidle module and cpuidle driver(for states/info reporting). By original plan, these tasks will be all completed by the end of 3/4 term…
Well I want to show the power saving result on my laptop(i5-2520M CPU, 4G memory, 320GB harddisk), after enabling the cpuidle and native intel cpuidle module, I saved about 2.5watt. Note, such power saving is achieved after removing ipro1000 driver and disabling Tracker, Deskbar.
After then, I added support to get c-state information such as, how many c-states there are, how long does each cpu spend on each c-state. It works well, here is output of my laptop c-states report after booting up 1-2 minutes
C-STATE COUNT: 5 CPU0 C1-SNB 15904 21091650us C3-SNB 323 726222us C6-SNB 136 55531us C7-SNB 5305 66519576us CPU1 C1-SNB 10846 27279470us C3-SNB 223 477981us C6-SNB 111 132995us C7-SNB 4741 60377828us CPU2 C1-SNB 15784 21833087us C3-SNB 291 1098679us C6-SNB 116 316450us C7-SNB 4076 65310174us CPU3 C1-SNB 12503 19676736us C3-SNB 191 352467us C6-SNB 26 156587us C7-SNB 3858 68084986us
As can be seen, although we spent most time on C7 during idle, but the time spent on C1 state is still unsatisfied. It means there are still more wakeups. However finding and removing the root cause of those unnecessary wakeups is my future work after gsoc and need haiku experts hand.
So far, I have one remaining task during summer by my proposal – implement the acpi cpuidle module, so that old platforms and non-intel platforms can benefit the feature too.
