Re: Overall picture of cpufreq..

[Tomasz Chmielewski <mangoo@wpkg.org>]

Thomas Renninger schrieb:
> On Mon, 2008-01-14 at 08:08 +0100, Tomasz Chmielewski wrote:

(...)

>> It looks to me that ondemand governor doesn't have "the complete 
>> intelligence".
>>
>> For example, it doesn't detect CPU load coming from some kernel tasks, 
>> like kcryptd: reads/writes from a device crypted with dm-crypt will be 
>> very slow if one uses the ondemand governor, as CPU speed will always be 
>> set to the lowest possible (so there is not enough power to 
>> crypt/decrypt data).
>>
>> Ironically, this is the only case when starting bzip2 will speed up your 
>> disk access... Or, use a userspace governor.
>>
>>
>> See also http://bugzilla.kernel.org/show_bug.cgi?id=9729
> 
> I don't know about this one.
> AFAIK there has been some work done there, I expect the bug in the
> crypto area, not in cpufreq/ondemand layer.
> 
> A Xeon processor stepped down from 2800 to 350 looks bogus (maybe the
> new ones even can, not sure)

Quite the contrary - it's a pretty old Xeon which is i386 only.
Why does it look bogus to you, anyway?


> could it be that you are using
> p4-clockmode driver which is doing throttling, not frequency scaling,
> better try with acpi-cpufreq then.

Indeed, I am using p4-clockmod.

acpi-cpufreq doesn't work for me on that machine (p4-clockmod not loaded 
when I try to insert acpi-cpufreq):

# modprobe acpi-cpufreq
FATAL: Error inserting acpi_cpufreq 
(/lib/modules/2.6.23.12-pata-1/kernel/arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.ko): 
No such device



-- 
Tomasz Chmielewski
http://wpkg.org