Mailing List Archive: Linux: Kernel

Core i7 not scaling frequency down

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felix-linuxkernel at fefe

Jul 4, 2009, 1:37 PM

Post #1 of 3 (164 views)
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Core i7 not scaling frequency down

Hi,

I just got a Nehalem CPU and it works OK except that the fans are always
running full power and it produces heat like an oven.

$ cat /proc/acpi/processor/P001/info
processor id: 0
acpi id: 1
bus mastering control: yes
power management: yes
throttling control: no
limit interface: no
$

Oh, no throttling and no limit support? How can this be? I'm using
2.6.30 but this appears to be bogus; Windows scales down the CPU
frequency OK.

Does this mean my BIOS ACPI tables are bogus?

I get this message at boot time, but it appears to be unrelated:

ACPI Warning (tbutils-0246): Incorrect checksum in table [OEMB] - 00, should be FE [20090320]

Any ideas what I could do now to get the CPU to slow down?

Thanks,

Felix
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elendil at planet

Jul 4, 2009, 2:24 PM

Post #2 of 3 (141 views)
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Re: Core i7 not scaling frequency down [In reply to]

Felix von Leitner wrote:
> Any ideas what I could do now to get the CPU to slow down?

What cpu frequency governor are you using?

Take a look in /sys/devices/system/cpu/cpu0/cpufreq/. I'd suggest ensuring
you're using the "ondemand" governor as a first step in managing CPU
speed.

Cheers,
FJP
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arjan at infradead

Jul 5, 2009, 1:30 AM

Post #3 of 3 (133 views)
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Re: Core i7 not scaling frequency down [In reply to]

On Sat, 4 Jul 2009 22:37:32 +0200
Felix von Leitner <felix-linuxkernel[at]fefe.de> wrote:

> Hi,
>
> I just got a Nehalem CPU and it works OK except that the fans are
> always running full power and it produces heat like an oven.
>
> $ cat /proc/acpi/processor/P001/info
> processor id: 0
> acpi id: 1
> bus mastering control: yes
> power management: yes
> throttling control: no
> limit interface: no
> $
>
> Oh, no throttling and no limit support? How can this be? I'm using
> 2.6.30 but this appears to be bogus; Windows scales down the CPU
> frequency OK.

how do you determine linux isn't scaling down? PowerTOP?
(if not powertop.. you might want to use that ;-)

> ACPI Warning (tbutils-0246): Incorrect checksum in table [OEMB] -
> 00, should be FE [20090320]

that's pretty bad, but might not be a table critical for C/P states...

--
Arjan van de Ven Intel Open Source Technology Centre
For development, discussion and tips for power savings,
visit http://www.lesswatts.org
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