RE: Inspiron 6000 and CPU power saving

From: Pallipadi, Venkatesh
Date: Thu Oct 19 2006 - 13:27:44 EST




>-----Original Message-----
>From: linux-kernel-owner@xxxxxxxxxxxxxxx
>[mailto:linux-kernel-owner@xxxxxxxxxxxxxxx] On Behalf Of
>Michael (Micksa) Slade
>Sent: Sunday, October 15, 2006 7:18 PM
>To: linux-kernel@xxxxxxxxxxxxxxx
>Subject: Inspiron 6000 and CPU power saving
>
>I recently discovered that my Inspiron 6000 uses about 50% more power
>idling in linux than in windows XP. This means its battery life is
>about 2/3 of what it could/should be.
>
>I guessed it might be the CPU, and did some tests. The
>results strongly
>suggest as much. These are the results I got for power consumption in
>various situations.
>
>linux idle at 800MHz: 27W
>linux idle at 1600MHz: 36W
>linux raytracing at 800: 30W
>linux raytracing at 1600: 42W
>
>windows idle (presumably 800MHz): 16W
>windows raytracing (presumably 1600MHz): 36W
>
>I've tried ubuntu dapper and ubuntu edgy, and RIP 10 (rescue disk) and
>BBC 2.1 (rescue disk), and they all appear to have the same
>issue. The
>machine's BIOS has no APM so I can't try it for comparison.
>
>I've tried noapic and "echo n >
>/sys/module/processor/parameters/max_cstate", where n is 1 thru 4.
>Neither appear to have any affect.
>
>I need help digging deeper. I guess /proc/acpi/processor/CPU0/power
>could give some insight but I'm not sure how to read the
>numbers. That
>and "learn about ACPI" is all I can figure out so far.
>
>So where to from here? I am prepared to spend a significant amount of
>time researching and resolving the issue, so feel free to suggest
>reading the ACPI spec or whatever if that's what it's going to take.
>
>Mick.
>

Output of
#cat /proc/acpi/processor/CPU0/power/*
And
#cat /sys/devices/system/cpu/cpu0/cpufreq/*
Will be a good starting point.

Also, open a issue at bugme.osdl.org. It makes tracking the issues
easier that way.

Thanks,
Venki
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