Le dimanche 02 mai 2010 à 07:13 -0700, Arjan van de Ven a écrit :

quoted

Cn                Avg residency       P-states (frequencies)
C0 (cpu running)        (68.9%)         2.93 Ghz    46.5%
polling           0.0ms ( 0.0%)         2.80 Ghz     5.1%
C1 mwait          0.0ms ( 0.0%)         2.53 Ghz     3.0%
C2 mwait          0.0ms (31.1%)         2.13 Ghz     2.8%
                                        1.60 Ghz    38.2%

I bet your system advertizes C2 with the same latency as C1,
but with lower power... which means Linux will pretty much never
pick C1.... no matter how much you take Andi's patch.

this is a bios thing... and until we put in the patch to override the
bios values (I can dust it off but it might need a bit of tweaking
since it was against .31) Andi's patch alone won't cut it... you also
need a non-lying bios ;)

# pwd
/sys/devices/system/cpu/cpu15/cpuidle
# grep . */*
state0/desc:CPUIDLE CORE POLL IDLE
state0/latency:0
state0/name:C0
state0/power:4294967295
state0/time:0
state0/usage:0
state1/desc:ACPI FFH INTEL MWAIT 0x0
state1/latency:1
state1/name:C1
state1/power:1000
state1/time:433855186
state1/usage:126869
state2/desc:ACPI FFH INTEL MWAIT 0x10
state2/latency:64
state2/name:C2
state2/power:500
state2/time:198095020416
state2/usage:76287744

C2 latency seems to be 64  (us ?), while C1 seems to be 1

BIOS Information
	Vendor: HP
	Version: I24
	Release Date: 10/01/2009

# powertop
PowerTOP 1.11   (C) 2007, 2008 Intel Corporation 

Collecting data for 5 seconds 


Your CPU supports the following C-states : C1 C2 C3 
Your BIOS reports the following C-states : C1 C2 

C3 seems to be disabled in BIOS