Arjan van de Ven wrote:
> Dale Pontius wrote:
>> I have a Thinkpad R50, running Gentoo with 2.6.22-gentoo-r2 with the
>> HPET patches applied.
>>
>> Sometimes C3 gets used, and sometimes it doesn't - on a completely idle
>> machine.
>>
>> When at work, the machine is plugged into a port replicator, the lid is
>> shut, and a flat panel connected through a KVM is used for the
>> display. If I do the complete boot with the display visible on the
>> flat panel, it
>> appears that the processor will never go into C3. If after selecting
>> the kernel with grub, I switch the KVM over to the deskside, then C3
>> will get used. I'm not 100% certain about this pattern, but it seems
>
> one question: is your KVM USB based?
> USB is one of the "typical" reasons processors don't go to C3, esp if
> USB selective suspend isn't active.....
No, this KVM uses ps2 ports for K and M, and 15-pin VGA for V. At the
moment there are no USB devices in use. I just double-checked that. My
deskside has a 4-port hub, and that shows up on usbview. Nothing shows
on usbview on the laptop, so the port replicator does not appear as a
USB hub.
For this morning's boot I left the KVM pointed to the laptop, and indeed
C3 is visible in the listing, but is not used.
While I've been typing this, the laptop has been running Gentoo's
"emerge --sync". It just finished and I started powertop, preparing to
start unloading USB modules to see if I could get into C3. It's already
there. The listing is tacked onto the end. What seems odd to me is
that all of the numbers are essentially the same as the listing
yesterday, except that yesterday it was in C2, and today it's in C3.
Can you point me to the source that handles these state transitions, or
any documentation?
Thanks,
Dale Pontius
PowerTOP version 1.7 (C) 2007 Intel Corporation
Cn Avg residency (30s) P-states (frequencies)
C0 (cpu running) ( 0.1%)
C1 0.0ms ( 0.0%) 1500 Mhz 0.0%
C2 41.8ms ( 0.3%) 1400 Mhz 0.0%
C3 147.2ms (99.6%) 1200 Mhz 0.0%
600 Mhz 100.0%
Wakeups-from-idle per second : 6.8
no ACPI power usage estimate available
Top causes for wakeups:
25.9% ( 2.0) afs_rxevent : schedule_timeout (process_timeout)
16.2% ( 1.2) cpufreq-set : queue_delayed_work_on
(delayed_work_timer_fn)
13.2% ( 1.0) ifplugd : schedule_timeout (process_timeout)
11.0% ( 0.8) xfsbufd : schedule_timeout (process_timeout)
10.1% ( 0.8) <interrupt> : ehci_hcd:usb1, uhci_hcd:usb2,
uhci_hcd:usb3, uhci_hcd:usb4, Intel 82801DB-ICH4 Modem, Intel
82801DB-ICH4, eth0
6.6% ( 0.5) ip : e1000_intr (e1000_watchdog)
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