Re: ondemand cpufreq ineffective in 2.6.12 ?

Con Kolivas
2005-07-12T11:57:30Z

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On Tue, 12 Jul 2005 21:49, Eric Piel wrote:
> 07/12/2005 01:11 PM, Ken Moffat wrote/a écrit:
> > On Tue, 12 Jul 2005, Ken Moffat wrote:
> >> I was going to say that niceness didn't affect what I was doing, but
> >>I've just rerun it [ in 2.6.11.9 ] and I see that tar and bzip2 show up
> >>with a niceness of 10. I'm starting to feel a bit out of my depth here
> >
> > OK, Con was right, and I didn't initially make the connection.
> >
> > In 2.6.11, untarring a .tar.bz2 causes tar and bzip2 to run with a
> > niceness of 10, but everything is fine.
> >
> > In 2.6.12, ondemand _only_ has an effect for me in this example if I
> > put on my admin hat and renice the bzip2 process (tried 0, that works) -
> > renicing the tar process has no effect (obviously, that part doesn't
> > push the processor).
> >
> > So, from a user's point of view it's broken.
>
> Well, it's just the default settings of the kernel which has changed. If
> you want the old behaviour, you can use (with your admin hat):
> echo 1 > /sys/devices/system/cpu/cpu0/cpufreq/ondemand/ignore_nice
> IMHO it seems quite fair, if you have a process nice'd to 10 it probably
> means you are not in a hurry.

That's not necessarily true. Most people use 'nice' to have the cpu bound task
not affect their foreground applications, _not_ because they don't care how
long they take. I nice my kernel compiles and keep web browsing etc (actually
I run them SCHED_BATCH but this has the same effect with the default ondemand
governor now).

>
> Just by couriosity, I wonder how your processes are automatically
> reniced to 10 ?

Shell environment settings.

Cheers,
Con

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