Re: cpufreq stops working after a while

[Carlos Garcia Campos <carlosgc@gnome.org>]

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El mar, 15-08-2006 a las 09:49 +0200, Thomas Renninger escribió:
> On Sat, 2006-08-12 at 10:52 +0200, Erik Slagter wrote:
> > On Fri, 11 Aug 2006 14:25:26 -0400 Mark Lord <lkml@rtr.ca> wrote:
> > 
> > > One of my notebooks (Dell Latitude X1) has a 1.1GHz Pentium-M ULV processor.
> > > This chip can change CPU speeds from 600 -> 800 -> 1100 Mhz.
> > > 
> > > I use speedstep-centrino with it, and after boot all is usually okay.
> > > But after a few hours of operation, it stops shifting to the highest frequency
> > > even under continuous 100% load (or not).  Eventually it gets stuck at 600Mhz
> > > and stays there until I reboot.

I have the same problem. My laptop is Dell Latitude D600 (Intel(R)
Pentium(R) M processor 1.60GHz). If I'm compiling something, for
example, that takes a long time, scaling_max_freq is set to 600000 (the
lowest). If I try to echo 1600000 to scaling_max_freq it do nothing.
Only after some time if the cpu load is not high I can echoing 1600000
again and it works without need to reboot. 

> After a few hours, urgh.
> 
> Dells limit their frequency to lowest after unplugging AC and allow all
> freqs after some time (some secs) again.
> 
> There were two issues solved on the Dells some months ago:
> 
> - The frequency after you unplug AC adapter is already reduced by BIOS, 
>   that confused the cpufreq driver.
> - There was a race in sysfs writes. If you e.g. change governor or 
>   possibly some other cpufreq related sysfs file while the frequency
>   got limited by BIOS, the real max freq value got overridden by the
>   temporarily limited max freq value and you are stuck to lowest freq
>   forever.
> 
> Do you use any userspace daemon (cpuspeed, powersaved, ...) to control
> cpuspeed?

In my case I use conservative governor and kernel version is
2.6.18-rc4. 

> If yes, you should first try without. It should be enough to:
> - load your hw cpufreq module
> - load the ondemand governor module
> - echo ondemand >/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
> 
> If it still happens we know at least it can't be some kind of sysfs race
> again or userspace tools do not remember the wrong max_freq value. Then
> some debug output or how to reproduce this a bit faster would be nice...

It happens to me every time I try to compile something that takes a long
time (evolution, mozilla, even kernel)

> Maybe with something like that:
> LOAD_FACTOR=40   # adjust this one to the power of your machine to let
>                  # cpufreq switch up and down, or if it does not switch 
>                  # up and down in the beginning it should stay at
>                  # 800 (could be 5-20 on yours?),
>                  # check with (in separate console):
> # cd /sys/devices/system/cpu/cpu0/cpufreq/
> # watch -n1  cat scaling_cur_freq scaling_max_freq
> 
> for ((x=200;x<1000;x+=5));do
>     # give load
>     for ((y=0;y<$LOAD_FACTOR;y++)); do
>         echo "10 k 2 v p" |dc >/dev/null
>     done;
>     # then sleep
>     usleep $((x*1000))   # maybe the right value here triggers the bug?
>     echo "sleep $x milli secs"
> done;
> 
> Maybe it's triggered if you start some other process(es) while this is
> running?
> 
>     Thomas
> 
> 
> _______________________________________________
> Cpufreq mailing list
> Cpufreq@lists.linux.org.uk
> http://lists.linux.org.uk/mailman/listinfo/cpufreq

-- 
Carlos Garcia Campos (KaL)
   elkalmail@yahoo.es
   carlosgc@gnome.org
   http://carlosgc.linups.org
PGP key: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x523E6462

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