Processor C states and USB problem

DISCUSSION mike-Z92qn3yYq0hWk0Htik3J/[email protected] 2 participants 2 messages Jan 5, 2004 1 message not in the archive ACPI

lore

Share & tools

lore

mike-Z92qn3yYq0hWk0Htik3J/[email protected]

author

2004-01-05 08:41 UTC #0 lore raw

Recently I had problems with my network card and ACPI (see earlier posts for the problem and solution) so I thought I'd take a closer look at ACPI on this notebook (Acer Travelmate 800).

Looking at the proc entries for the processor I saw the following.

active state:            C3
default state:           C1
bus master activity:     80070020

states:
C1: promotion[C2] demotion[--] latency[000]
usage[00000010]
C2: promotion[C3] demotion[C1]
latency[001]usage[01077887]
*C3: promotion[--] demotion[C2] latency[085]
usage[00083507]

This looked pretty normal to me, apart from the fact that the processor was spending a lot of time in C3 although the notebook was idle.

Now I plugged in my USB mouse.

cat /proc/acpi/processor/CPU0/power

active state:            C2
default state:           C1
bus master activity:     ffffffff <---- USB is active

states:
C1: promotion[C2] demotion[--] latency[000]
usage[00000010]
*C2: promotion[C3] demotion[C1]
latency[001]usage[00871647]
C3: promotion[--] demotion[C2] latency[085]
usage[00077386]

The processor never left the C2 state.
After unplugging the mouse "bus master activity" showed normal values again.

Now for my two questions:

1.) Is it normal for the notebook to spend so much time in C3, even if it is idle?

2.) Why is an USB device screwing up the bus master activity, resulting in the processor never leaving C2?

/Michael

-------------------------------------------------------
This SF.net email is sponsored by: IBM Linux Tutorials. Become an expert in LINUX or just sharpen your skills. Sign up for IBM's Free Linux Tutorials. Learn everything from the bash shell to sys admin. Click now! http://ads.osdn.com/?ad_id=1278&alloc_id=3371&op=click

A message that is not in the archive (sent off-list or not yet received): [email protected]

Petr Olivka

2004-01-05 09:11 UTC #2 lore raw

I did ask about this problem in usb-devel-forum.

You can see answer:
http://sourceforge.net/mailarchive/message.php?msg_id=6249537

usb host use poll mode to get data from usb peripherals, and result is continuous busmaster activity.

poli

Quoted 51 lines · On Mon, 5 Jan 2004 mike-Z92qn3yYq0hWk0Htik3J/[email protected] wrote:

Recently I had problems with my network card and ACPI (see earlier posts for the problem and solution) so I thought I'd take a closer look at ACPI on this notebook (Acer Travelmate 800).
Looking at the proc entries for the processor I saw the following.
active state:            C3
default state:           C1
bus master activity:     80070020
states:
C1: promotion[C2] demotion[--] latency[000]
usage[00000010]
C2: promotion[C3] demotion[C1]
latency[001]usage[01077887]
*C3: promotion[--] demotion[C2] latency[085]
usage[00083507]
This looked pretty normal to me, apart from the fact that the processor was spending a lot of time in C3 although the notebook was idle.
Now I plugged in my USB mouse.
cat /proc/acpi/processor/CPU0/power
active state:            C2
default state:           C1
bus master activity:     ffffffff <---- USB is active
states:
C1: promotion[C2] demotion[--] latency[000]
usage[00000010]
*C2: promotion[C3] demotion[C1]
latency[001]usage[00871647]
C3: promotion[--] demotion[C2] latency[085]
usage[00077386]
The processor never left the C2 state.
After unplugging the mouse "bus master activity" showed normal values again.
Now for my two questions:
1.) Is it normal for the notebook to spend so much time in C3, even if it is idle?
2.) Why is an USB device screwing up the bus master activity, resulting in the processor never leaving C2?
/Michael

Quoted 10 lines

-------------------------------------------------------
This SF.net email is sponsored by: IBM Linux Tutorials. Become an expert in LINUX or just sharpen your skills. Sign up for IBM's Free Linux Tutorials. Learn everything from the bash shell to sys admin. Click now! http://ads.osdn.com/?ad_id=1278&alloc_id=3371&op=click
_______________________________________________
Acpi-devel mailing list [email protected]
https://lists.sourceforge.net/lists/listinfo/acpi-devel