Re: Processor C states and USB problem

[Michael Guntsche <mike-Z92qn3yYq0hWk0Htik3J/w@public.gmane.org>]

On Fri, 9 Jan 2004 09:35:53 -0800
"Randy.Dunlap" <rddunlap-3NddpPZAyC0@public.gmane.org> wrote:

> On Fri, 9 Jan 2004 16:54:21 +0100 Michael Guntsche <mike-Z92qn3yYq0hWk0Htik3J/w@public.gmane.org>
> wrote:
> 
> | On Fri, 09 Jan 2004 11:15:22 +0100
> | Diego SANTA CRUZ <Diego.SantaCruz-p8DiymsW2f8@public.gmane.org> wrote:
> | 
> | > On Fri, 2004-01-09 at 11:05, Petr Olivka wrote:
> | > > in 2.4 kernel I have to unload all usb modules. Then power drop
> | > > to C3 state. If I remember, only usbcore can be loaded (on my
> | > > D600).
> | > > 
> | > 
> | > But even booting with init=/bin/sh and without ever loading any
> | > USB module I get permanent bus mastering activity. Any ideas?
> | 
> | I see the same on my notebook with a 2.4 kernel. Sometimes it works,
> | but most of the time there is Bus master acitivty.
> | With 2.6 I only see that if I have a USB device plugged in (mouse)
> | that gets polled.
> 
> It seems like one of the early usb uhci host controller drivers (HCDs)
> generated lots of bus master activity.  Are you sure that uhci or
> usb-uhci is not loaded (in the 2.4 problem case), even though no
> USB device drivers are loaded?
> 
Hmm, I did some tests and found out the following.

With USB modules loaded

	bus master activity:     ffffffff

With USB modules removed, the number goes down, but the processor still
stays in C2 most of the time.


In 2.6 I only get "ffffffff" if the mouse is plugged otherwise the
notebook spends more time in C3.
Since I am using 2.6 nowadays (PREEMPT being one of the main reasons),
this is not very important for me.

On a side note.
Do you have an idea why I no longer have performance management and the limit interface with 2.6?
I don't use those two myself, I just noticed it while testing ACPI in 2.6. 

/proc/acpi/processor/CPU0/info:
processor id:            0
acpi id:                 0
bus mastering control:   yes
power management:        yes
throttling control:      no
performance management:  no <-- yes on 2.4
limit interface:         no <-- yes on 2.4

This is an Acer 800 notebook with a Pentium M processor.

/Michael


 


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