Red Hat Bugzilla – Bug 444848
Kpowersave: can't select powersave cpu frequency policy
Last modified: 2009-03-19 15:49:25 EDT
Hi - Attempting to select powersave cpu frequency policy fails in KDE with
kpowersave. Get error: WARNING: CPU Freq Policy Powersave could not be set.
Cause: cpufreq_powersave kernel module is not loaded.
Workaround: sudo modprobe cpufreq_powersave
Why is cpufreq_powersave built as a module when _performance and _userspace are
$ grep CPU_FREQ_GOV /lib/modules/`uname -r`/build/.config
Problem happens with both kernels:
$ rpm -q kernel
System is a Dell Inspiron 8200.
$ cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 15
model : 2
model name : Mobile Intel(R) Pentium(R) 4 - M CPU 1.80GHz
stepping : 7
cpu MHz : 1800.000
cache size : 512 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 2
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 mtrr pge mca cmov pat pse36
clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe up pebs bts sync_rdtsc cid
bogomips : 3590.99
clflush size : 64
> Why is cpufreq_powersave built as a module when _performance and _userspace
> are built-in?
excellent question, better asked of kernel devs.
Not sure what kpowersave can do about cpufreq_powersave not being loaded.
(In reply to comment #1)
> > Why is cpufreq_powersave built as a module when _performance and _userspace
> > are built-in?
> excellent question, better asked of kernel devs.
That's why I filed under kernel...is this not the place to ask their input?
> Not sure what kpowersave can do about cpufreq_powersave not being loaded.
As an unprivileged user-space tool, I didn't think it could or should, which is
why I filed under kernel rather than kpowersave.
> That's why I filed under kernel
Umm, no, Component = kpowersave
I can reassign it if you want. :)
oops, under kpowersave was my initial selection, but I'm sure I changed it
before clicking 'save changes', oh well, I think I may have done it (if not,
Thanks, we'll see what the kind kernel folks have to say.
first, kpowersave shouldn't be blindly assuming that powersave is available. It
should only offer the governors that are available under
For this reason, I'm reassigning this back to kpowersave, as this is a bug that
should be fixed.
As for why it's not-builtin.. Think about what happens when its built in whilst
you're booting up, and immediately the cpu goes to power save mode. Suddenly
we're taking longer to boot up for no good reason.
The powersave governor isn't universally useful, it has some corner cases where
it's useful where the user knows better than say, ondemand, but in the general
case, it shouldn't be used.
performance is built in because, well it makes no difference.
userspace is built in because until it's configured by userspace scripts to do
something, it also makes no difference.
thx! /sys/devices/system/cpu/cpu*/cpufreq/scaling_available_governors looks like
Thanks, Rex. As you code around this, please try to give the user a clue that
if they load cpufreq_powersave, they will have additional functionality - i.e.,
don't just remove the menu item... maybe leave them grayed out? And while
you're rootin' 'round in there, how about supporting cpufreq_conservative, or
any governor that's in scaling_available_governors? Thanks!
The problem seems to still exist in Fedora 10. Before I was using Kubuntu 8.10 which supports powersave which gave me about 30 min more battery time.
I think it would be a good thing to load this module default but not use it as default governor.
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Reassigning -> F10.
Fwiw, I'd recommend not using kpowersave anymore, kde(4) on F9/F10 uses guidance-power-manager by default now.
I'm using guidance-power-manager but I'm not able to select the "powersave" profile until I load it manually through modprobe cpufreq_powersave before login.
Well I think this bug can be closed as "wontfix".
closing wontfix kpowersave has been dropped in favour of other options