[Wiltshire] Linux 2.6.28, ondemand governor and nice 19 processes

Robert RobertCL at iname.com
Sun Feb 22 21:31:16 UTC 2009


It's my own kernel, not the Gentoo one.  Any idea what settings I should 
be checking?

Ondemand is working, because it switches between 1.6Ghz and 2.4Ghz 
depending on whats running.  The problem is that even de-niced processes 
cause it to step up to 2.4Ghz.

I don't have cpufreq-info, but according to the files in /sys/.... I 
have ondemand selected and ignore_nice_load is set to 1 for all cores...

Robert.

Richard Reynolds wrote:
> BTW whats does your cpufreq-info say?
> 
> Can you set limits still with cpufreq-set?
> 
> 2009/2/22 Richard Reynolds <richard at uberpussy.net>:
>> Have you rolled your own kernel or used a Gentoo one? It could be that
>> the default options have changed. Fire up your kernel config and check
>> the settings, sounds like it isn't kicking in at all.
>>
>> It may also be the case that your CPU is an unlucky one this update as
>> there are various instances where the governor code doesn't work due
>> to CPUs own governors etc. It may well be fixed in the next
>> incarnation
>>
>> 2009/2/22 Robert <RobertCL at iname.com>:
>>> Hello,
>>>
>>> I'm hoping someone will be able to help with a problem I've been
>>> experiencing ever since I upgraded to 2.6.28
>>>
>>> I run Boinc (seti at home, etc) as a background process on my quad core
>>> server at a nice level of 19 and I'm using the ondemand CPU governor.
>>>
>>> Before upgrading to 2.6.28 processes running at nice 19 didn't cause the
>>> CPU frequency to step up, so it ran at it's lowest clock speed, which
>>> was perfect because it "saved" power and kept temperatures down.
>>>
>>> Since upgrading to 2.6.28, however it seems that this is not the case.
>>> So running Boinc causes all my CPU's to run at full clock speed all of
>>> the time, which I don't want - not only because it generates more heat
>>> and uses more power, but it also seems to interfere with processes
>>> running at higher nice levels, which I never really had a problem with
>>> before.
>>>
>>> I've tried everything I can think of to get back to the previous
>>> behaviour, but I'm at a bit of a loss what to search for or where to ask
>>> about this!  Some (useful?) output below.
>>>
>>> As a workaround, I've currently limited the CPU time in the Boinc
>>> manager to only use 50% of the available CPU's which means that 2 cores
>>> run at 2.4GHz and two run at 1.6GHz, but this doesn't seem to be the
>>> right solution and still causes the box to run hotter than if both idle
>>> at 1.6GHz all the time
>>>
>>> Any suggestions appreciated!
>>> Robert.
>>>
>>>
>>> robert at quad ~ $ cat /proc/version
>>> Linux version 2.6.28.4 (root at quad) (gcc version 4.1.2 (Gentoo 4.1.2
>>> p1.1)) #6 SMP PREEMPT Sun Feb 8 12:42:20 GMT 2009
>>>
>>> robert at quad ~ $ cat /sys/devices/system/cpu/cpu?/cpufreq/scaling_governor
>>> ondemand
>>> ondemand
>>> ondemand
>>> ondemand
>>>
>>> robert at quad ~ $ cat
>>> /sys/devices/system/cpu/cpu?/cpufreq/ondemand/ignore_nice_load
>>> 1
>>> 1
>>> 1
>>> 1
>>>
>>> robert at quad ~ $ cat /proc/cpuinfo |grep MHz
>>> cpu MHz         : 1600.000
>>> cpu MHz         : 2400.000
>>> cpu MHz         : 1600.000
>>> cpu MHz         : 2400.000
>>>
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>>>
> 
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