AMD64 overclock issue with 2.6.16 but not with 2.6.15

AMD64 overclock issue with 2.6.16 but not with 2.6.15

[JimD]

Do any one know of any other issues with amd64 and the
2.6.16 series?  I have run into a weird issue.

I have an AMD64 3200+ that runs at 2 GHz and runs *very* cool at about
34c.  My motherboard makes it pretty easy to overclock so I have
overclocked the 3200+ to 2.2 GHz and it has been running very stable
and still only around 39c.

When I was runing overclocked in 2.6.15 /proc/cpuinfo would show:

jim@keelie$ cat /proc/cpuinfo
processor       : 0
vendor_id       : AuthenticAMD
cpu family      : 15
model           : 47
model name      : AMD Athlon(tm) 64 Processor 3200+
stepping        : 2
cpu MHz         : 2200.000
cache size      : 512 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 1
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr
                  pge mca cmov pat pse36 clflush mmx fxsr sse sse2
                  syscall nx mmxext fxsr_opt lm 3dnowext 3dnow pni
                  lahf_lm ts fid vid ttp tm stc
bogomips        : 4409.17


Now with 2.6.16 it shows:

jim@keelie$ cat /proc/cpuinfo
processor       : 0
vendor_id       : AuthenticAMD
cpu family      : 15
model           : 47
model name      : AMD Athlon(tm) 64 Processor 3200+
stepping        : 2
cpu MHz         : 2000.000
                 ^^^^^^^^^^
<snip>
bogomips        : 4409.17


The bogomips are showing the same though the kernel is not reporting
the correct MHz.  If I reboot and check the BIOS, the correct MHz is
reported.  I have not run any CPU benchmarks to see if performance is
really going back down to 2000 MHz.

Does anyone have a clue what could be causing this?

Jim

Re: AMD64 overclock issue with 2.6.16 but not with 2.6.15

[Alistair John Strachan]

On Wednesday 29 March 2006 20:35, JimD wrote:
> Do any one know of any other issues with amd64 and the
> 2.6.16 series?  I have run into a weird issue.
[snip]
> The bogomips are showing the same though the kernel is not reporting
> the correct MHz.  If I reboot and check the BIOS, the correct MHz is
> reported.  I have not run any CPU benchmarks to see if performance is
> really going back down to 2000 MHz.
>
> Does anyone have a clue what could be causing this?

At a guess, it sounds like you're trying to use cpufreq on an overclocked CPU, 
a definitely no-no. Check your config for this option, remove it if desired.

-- 
Cheers,
Alistair.

'No sense being pessimistic, it probably wouldn't work anyway.'
Third year Computer Science undergraduate.
1F2 55 South Clerk Street, Edinburgh, UK.

Re: AMD64 overclock issue with 2.6.16 but not with 2.6.15

[JimD]

On Wed, 29 Mar 2006 20:54:09 +0100
Alistair John Strachan <s0348365@sms.ed.ac.uk> wrote:

> At a guess, it sounds like you're trying to use cpufreq on an
> overclocked CPU, a definitely no-no. Check your config for this
> option, remove it if desired.

mnt/sda/usr/src/linux-2.6.15-gentoo-r7
jim@keelie$ grep -i cpufreq .config
# CPUFreq processor drivers
CONFIG_X86_ACPI_CPUFREQ=y
CONFIG_X86_ACPI_CPUFREQ_PROC_INTF=y


/mnt/sda/usr/src/linux-2.6.16-gentoo
jim@keelie$ grep -i cpufreq .config
# CPUFreq processor drivers
CONFIG_X86_ACPI_CPUFREQ=y
CONFIG_X86_ACPI_CPUFREQ_PROC_INTF=y

If I boot into 2.6.15 /proc/cpuinfo show the correct info and the AMD
cool-n-quite thingy is working real well.  It put the processor at 1100
MHz or instantly ramps up to 2200 MHz.  If I boot into 2.6.16, the AMD
cool-n-quite thingy works, but now the processor goes down to 1000 MHz
or 2000 MHz.

I will recompile 2.6.16 without cpufreq and see if that help.

Jim

Re: AMD64 overclock issue with 2.6.16 but not with 2.6.15

[Philip Lawatsch]

Alistair John Strachan wrote:
> On Wednesday 29 March 2006 20:35, JimD wrote:
>> Do any one know of any other issues with amd64 and the
>> 2.6.16 series?  I have run into a weird issue.
> [snip]
>> The bogomips are showing the same though the kernel is not reporting
>> the correct MHz.  If I reboot and check the BIOS, the correct MHz is
>> reported.  I have not run any CPU benchmarks to see if performance is
>> really going back down to 2000 MHz.
>>
>> Does anyone have a clue what could be causing this?
> 
> At a guess, it sounds like you're trying to use cpufreq on an overclocked CPU, 
> a definitely no-no. Check your config for this option, remove it if desired.

Why is this a nono? I've been using that for quite a while without
problems. It seems that even though I overclocked it the system is
stable at all voltage / frequency steps. (I only modified the reference
clock and not the core voltages)

Also, 2.16 only shows a wrong value, the cpu is clocked at the "correct"
(overclocked) frequency, at least the bogomips value matches what I'm
expecting.

kind regards Philip