Re: ondemand cpufreq ineffective in 2.6.12 ?

[Con Kolivas <kernel@kolivas.org>]

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. Although I 
complained lightly initially when this change was suggested, I didn't realise 
it was actually going to become standard. 

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. 

Con

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