Re: [gentoo-amd64] complete crash with ondemand scheduler

[Joshua Hoblitt]

On Sun, Aug 05, 2007 at 04:29:43PM +0200, Beso wrote:
> i don't want to have to adjust it. i want it to step by default as i need,
> and if there are daemons and better governors (the conservative one is
> better in my opionion) i don't really understand why i should something that
> will bother me with tunings when there are things that don't need them and
> which perform better?!

So you'd rather install and have to configure an additional userspace
daemon then have to adjusting a single parameter in sysfs?  I don't
understand the logic of that.   This is not to say that there aren't good
reasons for using a userspace governor but in the simple case of only
scaling the CPUs frequency in reason to load it is not required, not
necessary, and just adds an extra piece of software to your system that
will wake your CPU up from a deep C state (wasting power).

You have in no way explained what your criteria for "perform better",
quantified the claim of "very bad" performance or why this discussion is
even specific to amd64 CPUs.

I'm not interested in arguing with you about this.  I just don't want to
leave your false claims unchallenged for the others reading this list as
power management is becoming a serious issue that all system
administrators need to deal with.  That last thing we need is FUD
floating around.

>
> 2007/8/5, Joshua Hoblitt <jhoblitt@××××××××××.edu>:
> >
> > On Sun, Aug 05, 2007 at 09:24:17AM +0200, Bernhard Auzinger wrote:
> >
> > > I think you are wrong, because the ondemand governor does also switch
> > between
> > > all available frequencies. For example my amd64X2 is capable of
> > > 1000,1800,2000,2200,2400MHz and the ondemand governor does switch very
> > well
> > > between these frequencies if needed.
>
>
> i repeat: on my 2 systems it didn't worked in that way, so i don't want to
> spend time bothering about tunings when there is really no need for that.

I suggest that you try reading the documentation for the ondemand
governor.  You can find it in the kernel sources as:

	Documentation/cpu-freq/governors.txt 

If you don't believe the documentation (or me), why don't you just try
adjusting the ondemand governors polling interval?

	echo ondemand > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
	cat /sys/devices/system/cpu/cpu0/cpufreq/ondemand/sampling_rate_max >
/sys/devices/system/cpu/cpu0/cpufreq/ondemand/sampling_rate

Cheers,

-J

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