ondemand: cpu load calculation with kernel processus

ondemand: cpu load calculation with kernel processus

[Nicolas Capit]

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Hello,

I am running a Debian unstable with a kernel 2.6.21-1-686 and using
modules powernow_k8 and cpufreq_ondemand.

My configuration with the ondemand governor seems to work very well
except when my cpu is busy by the kernel processus kcryptd. The cpu is
100% busy but the frequency is not increased.
(I am using the module dm_crypt to encrypt my home filesystem)

So my question is:
Does the ondemand governor calculate the load of the machine with user
level and *kernel* level processus?


Thanks,

Nicolas.


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Re: ondemand: cpu load calculation with kernel processus

[Len Brown]

On Thursday 31 May 2007 17:57, Nicolas Capit wrote:
> Hello,
> 
> I am running a Debian unstable with a kernel 2.6.21-1-686 and using
> modules powernow_k8 and cpufreq_ondemand.
> 
> My configuration with the ondemand governor seems to work very well
> except when my cpu is busy by the kernel processus kcryptd. The cpu is
> 100% busy but the frequency is not increased.
> (I am using the module dm_crypt to encrypt my home filesystem)
> 
> So my question is:
> Does the ondemand governor calculate the load of the machine with user
> level and *kernel* level processus?

both user and kernel time should count as busy time.

do the cpu stats exposed by top show that you have idle time available?

-Len

Re: ondemand: cpu load calculation with kernel processus

[Nicolas Capit]

On Thu, 31 May 2007 20:57:45 -0400
Len Brown <lenb@kernel.org> wrote:

> On Thursday 31 May 2007 17:57, Nicolas Capit wrote:
> > Hello,
> > 
> > I am running a Debian unstable with a kernel 2.6.21-1-686 and using
> > modules powernow_k8 and cpufreq_ondemand.
> > 
> > My configuration with the ondemand governor seems to work very well
> > except when my cpu is busy by the kernel processus kcryptd. The cpu is
> > 100% busy but the frequency is not increased.
> > (I am using the module dm_crypt to encrypt my home filesystem)
> > 
> > So my question is:
> > Does the ondemand governor calculate the load of the machine with user
> > level and *kernel* level processus?
> 
> both user and kernel time should count as busy time.
> 
> do the cpu stats exposed by top show that you have idle time available?

Ok I am sorry for the noise :-(
My program that get the CPU stats is buggy... with top, effectively the
CPU is 0% idle but 10%us and 90%wa
(wa : Amount of time the CPU has been waiting for I/O to complete.)

Except if increasing the CPU frequency will reduce I/O wait time, the
cpufreq_ondemand works well...


> 
> -Len
>