F14 cpuspeed / ondemand broken?

["Jóhann B. Guðmundsson"]

On 12/24/2010 05:59 AM, Steven Haigh wrote:
> Anyone have any ideas on this? :\

BIOS/platform issueis a common cause for the problem you are describing.

First is to see what scaling frequency are offered and you can do so by 
running...

"cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies"

Next is to check what bios_limit the kernel sees and you can do so by 
running...

"cat /sys/devices/system/cpu/cpu0/cpufreq/bios_limit".

If "bios limit" reports the highest available scaling frequency while 
running plugged in and the lowest available scaling frequency when 
unplugged as in running on battery it is not the culprit.

Just run "watch -n1 "cat 
/sys/devices/system/cpu/cpu*/cpufreq/bios_limit"" and plug/unplug/plug 
on your laptop and the frequency should change from highest to lowest to 
highest again.

If it does not change frequency on battery or on AC or at specific temp 
or with a specific AC adapteryou need to upgraded your bios to the 
latest for your manufacturer and search for SpeedStep, CPU frequency, 
P-state or power management related options ( often there are some knobs 
there that need to be set to "performance" ) in the bios and try 
changing it.

If turning all the bios knobs from "power save" or similar to 
"performance" or similar does not change the bios_limit you can override 
it by adding "processor.ignore_ppc=1" to the kernel line in grub or run 
"echo 1 > /sys/module/processor/parameters/ignore_ppc" to tweak it 
during runtime however be aware that there must be a reason why the 
vendor/OEM is limiting your frequency in the first place.

If "bios_limit" is not the cause for this start by trying the latest 
kernel versions for .35 .36 and .37 in koji and see if it's fixed in any 
of them if not you will need to file a bug report and make sure the 
kernel is compiled with CPU_FREQ_DEBUG=y and you boot with 
"cpufreq.debug=7" or run "echo 7 > 
/sys/module/cpufreq/parameters/debug"to tweak it during runtime and then 
attach "dmesg > dmesg.txt"  along with the output from "for x in 
/sys/devices/system/cpu/cpu0/cpufreq/*;do echo $x;cat $x;done && for x 
in /sys/devices/system/cpu/cpu0/cpufreq/ondemand/*;do echo $x;cat 
$x;done" to your report which should provide the maintainer with 
sufficient info to start working on your report.

Also take a look at various commands that come with the cpufrequtils 
package like cpufreq-info etc..

JBG
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