Re: ondemand cpufreq ineffective in 2.6.12 ?

Eric Piel
2005-07-12T07:58:58Z

11.07.2005 23:55, Con Kolivas wrote/a écrit:
> On Tue, 12 Jul 2005 05:45, Ken Moffat wrote:
>
>>On Mon, 11 Jul 2005, Ken Moffat wrote:
>>
>>>Hi,
>>>
>>> I've been using the ondemand governor on athlon64 winchesters for a few
>>>weeks. I've just noticed that in 2.6.12 the frequency is not
>>>increasing under load, it remains at the lowest frequency. This seems
>>>to be down to something in 2.6.12-rc6, but I've seen at least one report
>>>since then that ondemand works fine. Anybody else seeing this problem ?
>>
>> And just for the record, it's still not working in 2.6.13-rc2. Oh
>>well, back to 2.6.11 for this box.
>
>
> I noticed a change in ondemand on pentiumM, where it would not ramp up if the
> task using cpu was +niced. It does ramp up if the task is not niced. This
> seems to have been considered all round better but at my end it is not - if
> it takes the same number of cycles to complete a task it does not save any
> battery running it at 600Mhz vs 1700Mhz, it just takes longer. Yes I know
> during the initial ramp up the 1700Mhz one will waste more battery, but that
> is miniscule compared to something that burns cpu constantly for 10 mins. Now
> I'm forced to run my background tasks at nice 0 and not get the benefit of
> nicing the tasks, _or_ I have to go diddling with settings in /sys to disable
> this feature or temporarily move to the performance governor.
echo 1 > /sys/devices/system/cpu/cpu0/cpufreq/ondemand/ignore_nice
Put it once for all in your initscript :-)

> Although I
> complained lightly initially when this change was suggested, I didn't realise
> it was actually going to become standard.
I like it because it avoids that any background task which is ran makes
the fans turning like hell. It's also very advantageous with tasks like
screensavers or a la seti@home (but few people have this on their laptop).

>
> To me the ondemand governor was supposed to not delay you at all, but cause as
> much battery saving as possible without noticeable slowdown...
>
> Oh well you can't please everyone all the time.
It's a tradeoff :-)

Ken, does this solve your problems (but that seems strange that all your
tasks are nice'd) ?

Eric