PowerBook G4 fans keep coming on?

[Seraphim9]

Hey all. I have a PowerBook G4 with Kubuntu 12.04 and the fan(s)? keeps coming on. They will stop for a few minutes and then fire right back up even when I'm doing the most minimal of tasks. They continue turning off and on, off and on throughout the entire session. When I run the top command in the terminal nothing seems to be hogging the CPU. When I boot into OSX everything runs as quiet as a mouse with the fans only coming on after multiple hours of use. Is Kubuntu overheating my laptop? Or taxing the GPU? Has anyone else experienced this? Thanks in advance.

[SecretCode]

Fan speed should be pretty much related to cpu temperature, which in turn could be driven by cpu load, or i/o load or gpu load or other things. If you add the "System Monitor" widget to your panel or desktop, you can monitor CPU temperature and so on. This might help you understand what's triggering it.

Do you have cpu frequency scaling? /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor should show 'ondemand'

Lots of people seem to experience different fan behaviour between OSes on dual boot machines. For me, Ubuntu was much quieter than Windows on my last machine - can't really say on this one. It could be due to greater load caused by more processor or disk activity - but it could also be due to different set-points for when the fans come on. I've seen a "fancontrol" package that offers to help with this, but it doesn't seem to be in the repos now. Developers seem not very interested in this, perhaps because each motherboard is different, and perhaps because if you get it wrong you can fry your machine.

Do your fans only have "on" and "off" speeds? On my ASUS laptop, they vary smoothly which is much less disturbing than a sharp off-on ... but this is of no help to you!

[Seraphim9]

I have discovered that the scaling_governor is set to 'performance'. How can I change this to 'ondemand'? Also I tried the System Monitor widget but the CPU temperature widget doesn't seem to work. Thanks for your help.

[SecretCode]

Re the cpu temperature not working, maybe you don't have the right sensors available.

Install lm-sensors (this will do nothing if it's already installed)

sudo apt-get install lm-sensors

then run

sensors

To set it to 'ondemand' it may be as simple as writing that string to that file (using 'tee' to get around the limitations of sudo)

echo ondemand | sudo tee /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

and similarly for cpu1 etc. (But I'm not sure if this will persist through a reboot.)

If it doesn't work check that

cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors

includes ondemand

And/or go and read about kernel cpu frequency scaling ... linux-kernel:cpufreq [Analog Devices | Mixed-signal and Digital Signal Processing ICs] ... CPU Frequency Scaling ... Enabling CPU Frequency Scaling « Ubuntu Blog ...

[Seraphim9]

I installed the lm-sensors and ran the sensors command. It returned 'No sensors detected!' It recommended running sensors-detect. I did. At the end of the test it indicated that no sensors were detected or the sensors were not supported. It gave a link to a lm-sensors wiki page. More homework. Yea. I find it hard to believe that there are NO sensors because OSX must have some way of regulating temperature and fan control so I'm assuming that the sensors are just not supported in Linux.

I also ran the sudo tee command and it did not change the setting of the scaling_governor file. It still reads 'performance'. And I ran the final command and 'ondemand' IS listed as one of the available governors. Thanks for the links. I will do some more research on my end.

[SecretCode]

so I'm assuming that the sensors are just not supported in Linux.

That would be my guess too, sadly

[SecretCode]

A thought: have a look at powertop (needs to be run with sudo). It's in the repos if not installed by default.

Just don't change any "tunables" without researching them first!

[Seraphim9]

I installed powertop via the terminal and did a system reboot. When I tried to run powertop it returned this error message in the terminal.

Cannot load from file /var/cache/powertop/saved_results.powertop
Cannot load from file /var/cache/powertop/saved_parameters.powertop

I did notice something the other day though. I was on my laptop for a couple of hours and I didn't hear a peep out of the fans(normally the kick on almost immediately). I noticed that all the windows in my room were open and the ambient temperature was much cooler which made me think perhaps OSX simply has a higher temperature setting at which the fans kick on and Kubuntu has a lower threshold which is why they run more frequently. Is there anyway to change this setting? Maybe if I kicked it up 5 degrees of so the fans wouldn't run so constant. Just a thought. I guess I could also jump inside the refrigerator with my laptop when I want a quiet Kubuntu session.

[SecretCode]

Those error messages aren't a problem.

You may be right about the lower thresholds set in *buntu ... but I can't advise how to change them sorry.

[SteveRiley]

I have discovered that the scaling_governor is set to 'performance'. How can I change this to 'ondemand'?

This is unusual, because ondemand has been the kernel's default governor for some time. Let's have a look through your syslog for any relevant error messages. What's the output of:

grep -iE 'ondemand|performance|governor' /var/log/syslog

[Seraphim9]

Here is the output of that command:

Sep 15 13:43:34 Frankenstein kernel: [    0.022996] MPC7450 family performance monitor hardware support registered
Sep 15 13:43:40 Frankenstein kernel: [   25.306253] ondemand governor failed, too long transition latency of HW, fallback to performance governor
Sep 15 13:44:41 Frankenstein kernel: [   85.768417] ondemand governor failed, too long transition latency of HW, fallback to performance governor
Sep 15 13:51:34 Frankenstein kernel: [    0.022995] MPC7450 family performance monitor hardware support registered
Sep 15 13:51:39 Frankenstein kernel: [   24.192722] ondemand governor failed, too long transition latency of HW, fallback to performance governor
Sep 15 13:52:40 Frankenstein kernel: [   84.529769] ondemand governor failed, too long transition latency of HW, fallback to performance governor
Sep 15 21:03:46 Frankenstein kernel: [    0.022994] MPC7450 family performance monitor hardware support registered
Sep 15 21:03:53 Frankenstein kernel: [   21.175451] ondemand governor failed, too long transition latency of HW, fallback to performance governor
Sep 15 21:03:53 Frankenstein pbbuttonsd: INFO: Script '/etc/power/pmcs-pbbuttonsd performance ac ' lauched but exitcode is not null
Sep 15 21:04:54 Frankenstein kernel: [   82.062795] ondemand governor failed, too long transition latency of HW, fallback to performance governor
Sep 15 21:39:41 Frankenstein kernel: [    0.022993] MPC7450 family performance monitor hardware support registered
Sep 15 21:39:46 Frankenstein kernel: [   24.625808] ondemand governor failed, too long transition latency of HW, fallback to performance governor
Sep 15 21:40:46 Frankenstein kernel: [   84.927336] ondemand governor failed, too long transition latency of HW, fallback to performance governor
Sep 16 12:03:43 Frankenstein kernel: [    0.023010] MPC7450 family performance monitor hardware support registered
Sep 16 12:03:48 Frankenstein kernel: [   24.629745] ondemand governor failed, too long transition latency of HW, fallback to performance governor
Sep 16 12:04:48 Frankenstein kernel: [   84.901434] ondemand governor failed, too long transition latency of HW, fallback to performance governor

[SecretCode]

All those lines

ondemand governor failed, too long transition latency of HW, fallback to performance governor

are almost certainly the source of the trouble.

Some web searching suggests that the p4-clockmod kernel module may have something to do with it

lsmod|grep clockmod

and a possible hard-coded value of

cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_transition_latency

Bug #432706 “cannot change governor from command line” : Bugs : “linux” package : Ubuntu makes interesting reading. Overlook the appearance of it being a bug "fixed" in a Lucid kernel...

[SteveRiley]

Thanks, SecretCode. Indeed, the transition latency error was what I suspected. From there, I was planning to Google a bit using that along with "powerbook" as search terms; it appears you've already done that.

[SecretCode]

I can Google a bit with the best.