Re: Inspiron 6000 and CPU power saving

From: Michael (Micksa) Slade
Date: Sat Oct 21 2006 - 07:46:53 EST


Pallipadi, Venkatesh wrote:





-----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


Done.

http://bugzilla.kernel.org/show_bug.cgi?id=7393

As part of this I've also tried vanilla 2.6.19-rc2 and done another small test. See the report.

Mick.

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