linux-kernel - Re: [gentoo-amd64] Is /proc/cpuinfo showing the actual frequency ?

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Date:	Thu, 19 Feb 2009 21:05:32 +0200
From:	Thanasis <thanasis@...r.hopto.org>
To:	gentoo-amd64@...ts.gentoo.org
CC:	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [gentoo-amd64] Is /proc/cpuinfo showing the actual frequency
 ?

on 02/19/2009 07:46 PM Paul Hartman wrote the following:
> On Thu, Feb 19, 2009 at 10:55 AM, Justin <justin@...chmitz.net> wrote:
>> Thanasis schrieb:
>>> on 02/19/2009 06:23 PM Justin wrote the following:
>>>> Thanasis schrieb:
>>>>
>>>>> # uname -a
>>>>> Linux wolfdale 2.6.28-gentoo-r2 #1 SMP PREEMPT Wed Feb 18 13:53:22 EET
>>>>> 2009 x86_64 Intel(R) Core(TM)2 Duo CPU E8400 @ 3.00GHz GenuineIntel
>>>>> GNU/Linux
>>>>>
>>>>> Overclocked the core 2 duo (E8400) from 3 to 4GHz using motherboard
>>>>> BIOS settings. In mswindblows I can see the overclocked frequency
>>>>> (when cpu is under load), in linux /proc/cpuinfo never shows beyond the
>>>>> stock 3GHz value.
>>>>>
>>>>> Q: Is /proc/cpuinfo showing the actual frequency?
>>>>>
>>>>>
>>>> Do you have frequency scaling active?
>>> Yes, but the /proc/cpuinfo I showed, was with the max frequency ever
>>> displayed (under load).
>>>
>> AFAIK the scaling will interfere with OC. Try to disable it and check
>> again.
>
> I just did some googling and it seems that frequency scaling in linux
> only works with the stock speed steps, not the OC'ed speed.

I bet if I disable frequency scaling from BIOS, it will show 4GHz, because the 
funny thing is that inside a fully VM (guest) it shows the "real" frequency  ;-) 

# cat cpuinfo
processor    : 0
vendor_id    : GenuineIntel
cpu family    : 6
model        : 23
model name    : Intel(R) Core(TM)2 Duo CPU     E8400  @ 3.00GHz
stepping    : 10
cpu MHz        : 4050.236
cache size    : 6144 KB
fpu        : yes
fpu_exception    : yes
cpuid level    : 13
wp        : yes
flags        : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat 
clflush dts mmx fxsr sse sse2 ss syscall nx lm pni ds_cpl cx16 xtpr lahf_lm
bogomips    : 8111.05
clflush size    : 64
cache_alignment    : 64
address sizes    : 36 bits physical, 48 bits virtual
power management:

processor    : 1
vendor_id    : GenuineIntel
cpu family    : 6
model        : 23
model name    : Intel(R) Core(TM)2 Duo CPU     E8400  @ 3.00GHz
stepping    : 10
cpu MHz        : 4050.236
cache size    : 6144 KB
fpu        : yes
fpu_exception    : yes
cpuid level    : 13
wp        : yes
flags        : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat 
clflush dts mmx fxsr sse sse2 ss syscall nx lm pni ds_cpl cx16 xtpr lahf_lm
bogomips    : 8101.80
clflush size    : 64
cache_alignment    : 64
address sizes    : 36 bits physical, 48 bits virtual
power management:

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