[systemd-devel] cpufrequtils considered useless (was: systemd unit files for Debian based systems)

[Paul Menzel]

Am Dienstag, den 19.06.2012, 10:03 +0200 schrieb Lennart Poettering:
> On Mon, 18.06.12 21:56, Paul Menzel (paulepanter at users.sourceforge.net) wrote:

Dear Lennart,


[…]

> > > What is cpufrequitls for? Why would anybody fiddle with that? "ondemand"
> > > is the only CPU scheduler that makes sense, so what is this about? Also,
> > > you can change the CPU scheduler via simple sysfs writes, right? So why
> > > would you use a tool like "cpufreq" for this? tmpfiles should be
> > > entirely sufficient?
> > > 
> > > cpufreq stuff really appears to be sugar for -Oit-feels-so-much-faster-now freaks...
> > 
> > In Debian it is a recommendation of the package `gnome-applets`.
> > 
> >         $ LANG=C aptitude why cpufrequtils
> >         i   gnome         Depends    gnome-applets (>= 2.91)
> >         i A gnome-applets Recommends cpufrequtils
> > 
> > I guess it is useful to have an abstraction layer because directories
> > and files under `/sys` might change.
> 
> Nah, really, cpufrequtils should just go away. People should use the
> kernel APIs right away.

alright looking into why `cpufrequtils` is installed on my system I now
know the reasons. The frequency(?) modules are not loaded automatically
and therefore the init.d script shipped by `cpufrequtils` is needed.

        $ zless /usr/share/doc/gnome-applets/changelog.Debian.gz
        […]
        gnome-applets (2.24.2-1) experimental; urgency=low

          * es.po: updated Spanish translation from Francisco Javier Cuadrado. 
            Closes: #502236.
          * Recommend cpufrequtils. Closes: #448833.

The mentioned Debian bug reports #448833 [8] and #509827 [9] contain the
discussion.

Without the appropriate modules loaded – in my case `powernow_k8` – no
power saving features of the CPU are available.

        $ find /sys -iname '*cpufreq*'
        /sys/devices/system/cpu/cpufreq
        $ ls -l /sys/devices/system/cpu/cpufreq/
        insgesamt 0
        $ sudo modprobe powernow_k8
        $ ls -l /sys/devices/system/cpu/cpufreq/
        insgesamt 0
        drwxr-xr-x 2 root root 0 Jun 19 11:18 ondemand

So how is this supposed to work out of the box?


Thanks,

Paul


[8] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=448833
[9] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=509827
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