C-states only used _with_ load on Acer Extensa 5220 Celeron M Notebook (2.6.24 x64)

[Len Brown]

On Sunday 10 February 2008 09:05, Dennis Jansen wrote:
> I did enable all required kernel features, e.g. the cpuidle framework.
> 
> [   20.138326] CPU: L1 I cache: 32K, L1 D cache: 32K
> [   20.138436] CPU: L2 cache: 1024K
> [   20.138498] using mwait in idle threads.
> [   20.138567] CPU0: Thermal monitoring handled by SMI
> [   20.138573] CPU: Intel(R) Celeron(R) CPU          530  @ 1.73GHz stepping 01
> 
> The only thing unusual I see is:
> [   20.349762] PCI: Using MMCONFIG at e0000000 - efffffff
> [   20.351845] ACPI: EC: Look up EC in DSDT
> [   20.354080] ACPI: BIOS _OSI(Linux) query ignored via DMI
> [   20.354150] ACPI: If "acpi_osi=Linux" works better, please notify
> linux-acpi at vger.kernel.org
> [   20.354985] ACPI: Interpreter enabled
> [   20.355049] ACPI: (supports S0 S3 S4 S5)
> [   20.355301] ACPI: Using IOAPIC for interrupt routing
> [   20.356191] ACPI: EC: non-query interrupt received, switching to
> interrupt mode
> [   20.773458] ACPI: EC: GPE = 0x17, I/O: command/status = 0x66, data = 0x62
> [   20.773528] ACPI: EC: driver started in interrupt mode
> [   20.773623] ACPI: PCI Root Bridge [PCI0] (0000:00)
> [   20.774378] PCI quirk: region 1000-107f claimed by ICH6 ACPI/GPIO/TCO
> [   20.774448] PCI quirk: region 1180-11bf claimed by ICH6 GPIO
> 
> But "acpi_osi=Linux" does not change the situation. It seems like
> something prevents the cpu form using the C1/2-states, I only get
> about 0.3-1 % C1/2 with 99.7% idle and only 60 wakes/sec in powertop.
> But it gets more confusing:
> 
> When I start Skype, it grows to about 4000 wakes/sec, but the C-states
> are used _more_:  "PowerTOP version 1.9       (C) 2007 Intel
> Corporation
> Cn                 Verweildauer       P-States (Frequenzen)
> C0 (Prozessor läuft)    (93,9%)
> C1                0,0ms ( 0,0%)
> C2                0,0ms ( 6,1%)
> Wakes per second : 4070,7  Intervall: 3,0s
>   58,9% (372,7)             skype : do_nanosleep (hrtimer_wakeup)
>   14,8% ( 93,7)       <interrupt> : HDA Intel, uhci_hcd:usb2
>   13,0% ( 82,3)       <interrupt> : b43, uhci_hcd:usb4
>    2,8% ( 18,0)             skype : schedule_timeout (process_timeout)
>    2,4% ( 15,0)       <interrupt> : acpi
> 
> versus normal load:
> C0 (Prozessor läuft)    (98,9%)

98.9% C0 means that the system is busy all the time
and that looking at idle time is simply not interesting
b/c there really isn't any.

run top to figure out what is hogging the cpu and kill it.

cheers,
-Len

> C1                0,0ms ( 0,0%)
> C2                0,0ms ( 1,1%)
> Aufwachen pro Sekunde : 812,6   Intervall: 5,0s
>   30,7% ( 49,8)             opera : schedule_timeout (process_timeout)
>   23,5% ( 38,2)            kicker : schedule_timeout (process_timeout)
>    9,5% ( 15,4)       <interrupt> : uhci_hcd:usb3, ehci_hcd:usb7
>    9,5% ( 15,4)   USB Gerät  3-1 : Optical USB Mouse (Logitech)
>    7,0% ( 11,4)              Xorg : do_setitimer (it_real_fn)
>    6,5% ( 10,6)       <interrupt> : acpi
> 
> So am I mistaken or is there something wrong?
> Any hints what to check / what might help are very welcome.
> 
> Thanks
> 
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