Comment 18 for bug 1600599

While I have to agree with teo1978 that it did take a long time to find out why my performance was being compromised so heavily due to the lack of information that thermald provides to the log (involving a lot of red herrings and detours through pstate vs cpufreq, read-only frequency scaling properties, etc), I can report that cleaning out your fans with many shots of compressed air can really, really help avoid the problem of getting to the critical temperatures where performance must be seriously constrained.

Before my fan cleanup, "stress-ng --matrix 0" could cause my CPU to be reduced to the scaling_min_freq. After the cleanup, the frequency was between 60% to 80% of the max and better able to be controlled. (Sometimes it never goes back to scaling_max_freq until I reboot, I'm still not sure whose fault that is, though it only seems to happen when intel_pstate is included as a CoolingDevice in thermal-cpu-cdev-order.xml. I will try to reproduce it and get debug logs.)

Since I can't see my fan speeds even after running sensors-detect and loading all modules, I have them set to the max they can go all the time in my BIOS. The fans don't sound different when under high load or low load. stress-ng can send my temperature soaring to 98C without thermald but the fan speed sounds the same. So I can conclude that even with the fax at max, I still need the cooling techniques of thermald sometimes.

But seriously, it would have been so much easier to figure out what was going on if thermald wrote something, anything to the system log to note it was throttling CPU.