Intel SpeedStep and Hyperthreading causes system hang
 

Bit of a hardware dilemma!

I have an Intel Pentium D 3.00GHz running on an Asus P5ND2-SLI Deluxe motherboard, running openSUSE 10.3 on kernel 2.6.22.

When I *don't* enable Intel SpeedStep technology and/or hyperthreading in the BIOS, the system goes very sluggishly when doing anything remotely complex (running a processor-intensive application, doing 3D drawing, etc). When I *do* enable either or both of them, the system runs like a dream, but hangs within minutes. And I really mean *hang* - nothing shows up in error logs, but the system completely freezes - I can't switch to a text console, I can't even use Magic SysRq keys. The only thing that works is a total reboot.

Any ideas as to what would cause this?

With my VIA Epia system I had to disable the dynamic CPU clock change when in X - not doing this would hang my system. This means that if...
...returned "ondemand" or "conservative" the system would hang after a few minutes if I wouldn't change that value to "performance" or "powersave" with...
.
Hyperthreading used to work well with all my systems.

You say hyperthreading used to work well with all your systems - do you think this is some sort of kernel bug, then?

How would I go about changing my system so that the cpufreq governor is permanently set to Performance, say?

Change the kernel config under "Power management options => CPU frequency scaling" or add in your "etc/init.d" a script that executes the above statement after boot - there are probably other options.
The first thing I would try in your case is to install an older and/or a newer kernel version and see if that fixes the problem. I didn't try version 2.6.22 yet - still on 2.6.21 and didn't have any problems with speedstep.
Don't know about hyperthreading and it sounds very strange to me that if you don't enable hyperthreading & speedstep your system gets very slow. Perhaps you should disable both of them and check your logs in order to find out what's going on. Disabling speedstep in the BIOS should make the CPU run at full power and hyperthreading itself gives only 15% more power if enabled, so it shouldn't make a lot of difference if dis/ or enabled. :scratch:

Alas I tried this to no effect. The command executed succesfully but the system hung not long thereafter.

I've tried various versions of the kernel too, without luck. Incidentally both Hyperthreading and SpeedStep options are only available to me in the BIOS once I have selected "Limit CPUID MaxVal" to Enabled. Once either is "Enabled" though, the system seems to hang :(