Dell M4400 w/Intel P8600 not wanting to change to VIDS

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DeiBellum
Posts: 3
Joined: Fri 2. Jul 2010, 05:06

Dell M4400 w/Intel P8600 not wanting to change to VIDS

Post by DeiBellum » Fri 2. Jul 2010, 05:23

Hello,

I have recently installed PHC 3.2.2 onto a Slackware 13.1 x64 system (kernel 2.6.33.4 vanilla) with a p8600 processor. Having changed the VIDS in the phc_controls file, I noticed that the readmsr tool was showing that although the processor was trying to go to the VIDs specified it wouldn't make it there and just be stuck at the original values.

Here are the commands I have run thusfar from /sys/devices/system/cpu/cpu0/cpufreq. The semicolon separates the input from the output.

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cat phc_controls: 73:39 9:29 6:23 134:13
echo "73:30 9:24 6:15 134:10" >> phc_controls
When i examine the phc_controls file again it has the correct VIDs however with the readmsr tool this is what I get:

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bash-4.1# ./read_msr.py  --readmsr
MSRTOOL V0.2pre-3 started...

[cpu0] [CURRENT] FID:9 HID:0 DID:0 VID:29 
[cpu0] [TARGET]  FID:9 HID:0 DID:1 VID:30 
[cpu0] [HIGHEST] FID:9 (HID:0 DID:0) VID:29 (not sure if they exist here)
[cpu0] [LOWEST]  FID:6 (HID:0 DID:0) VID:23 (not sure if they exist here)
[cpu0] [SLFM]    FID:6 VID:13 
[cpu0] [IDA]     FID:9 VID:39 
[cpu0] [CURRENTLY ACTIVE FEATURES] IDA:0 EIST:1

[cpu1] [CURRENT] FID:9 HID:0 DID:0 VID:29 
[cpu1] [TARGET]  FID:9 HID:0 DID:1 VID:39 
[cpu1] [HIGHEST] FID:9 (HID:0 DID:0) VID:29 (not sure if they exist here)
[cpu1] [LOWEST]  FID:6 (HID:0 DID:0) VID:23 (not sure if they exist here)
[cpu1] [SLFM]    FID:6 VID:13 
[cpu1] [IDA]     FID:9 VID:39 
[cpu1] [CURRENTLY ACTIVE FEATURES] IDA:0 EIST:1
As you can see with cpu0, it has the correct target, but it never reaches that target even when changing frequencies.

from lsmod I have the intel-phc module loaded and acpi-cpufreq not loaded. (trying to load acpi-cpufreq results in nothing happening)

in my kernel config I have the ACPI CPU Frequency Scaling options acpi_cpufreq, cpufreq <insert governor here>, and the translation stats built as modules.

dmesg shows no errors for the ACPI system loading.

So any idea on where i might be going wrong? I have read over the documentation but i might have missed something or I just plain suck at this :)

the-fallen
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Joined: Wed 9. Jul 2008, 19:57

Re: Dell M4400 w/Intel P8600 not wanting to change to VIDS

Post by the-fallen » Fri 2. Jul 2010, 17:51

Heya,

the Intel Core2 CPU does not allow different voltages for each core.
So it adjusts the voltage to the highest value one of the cores currently needs ( even if the others do not need them .. it does not harm them ).

Try to adjust the same VIDs to both cores, that should work.

DeiBellum
Posts: 3
Joined: Fri 2. Jul 2010, 05:06

Re: Dell M4400 w/Intel P8600 not wanting to change to VIDS

Post by DeiBellum » Sat 3. Jul 2010, 16:49

The Fallen,

Thank you for the quick reply and what you have said definitely makes sense.

However, I have tried setting the command across both cores, and either this is just the SLFM not wanting to adjust the VID but the voltage was unable to drop to the set value even though it was assigned across both cores. I have not seen it change with a FID change due to the laptop being low on battery but this is what I have seen so far. I will try to force a frequency change next time and report back but this is what I have seen so far.


Cheers

DeiBellum
Posts: 3
Joined: Fri 2. Jul 2010, 05:06

Re: Dell M4400 w/Intel P8600 not wanting to change to VIDS

Post by DeiBellum » Sun 4. Jul 2010, 18:01

I can confirm that the VIDS are not being hit even with frequency changes.

It seems as if the cores want to hit them but every time they try they are forced to the original values. I will get a sporadic hit on the VID here and there but most of the time the cores are at the original VIDS trying to get to the ones assigned by linux-phc.

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