Most recent kernel where this bug did not occur: Unknown Distribution: Fedora Core 4 Hardware Environment: HP nx6125 laptop - Turion 64, ATI chipset, AMD powernow-k8 Software Environment: Fedora Core 4 with vanilla kernel.org kernel Problem Description: CPU frequency keeps dropping back to lowest setting. (1) Using the cpufreq "userspace" governor with the CPU frequency monitor Gnome Applet but WITHOUT the cpuspeed service on, it is possible to increase the CPU frequency to its maximum setting (2200MHz) (this is presumably just a GUI wrapper around a write to scaling_setspeed). However, with a typical busy system (compililing), the monitor applet shows the speed soon drops back to 800MHz and never recovers. Some kernel debugging (using the patch attached) has shown that an ACPI processor "PPC changed" notify event is received which causes the cpufreq policy to be updated, and the maximum frequency reduced. A second ACPI event is received a few seconds later as the PPC value is reset to its original (fastest) value, but the cpufreq policy is not updated by this and the max frequency stays low. (2) Running the cpuspeed daemon can improve this slightly. However, cpuspeed v1.2.1 will only change the CPU speed if the newly calculated speed (based on processor idle time) is DIFFERENT from the value calculated last time. This means that when ACPI changes the speed "behind its back" it causes great confusion. Steps to reproduce: Install a kernel with cpufreq, ACPI and the userspace governor (see attached CONFIG). Run a long compilation or other realistic load. Try to set speed to max (2200MHz?) using scaling_setspeed or Gnome applet. Peter Wainwright
Created attachment 7411 [details] Kernel configuration
Created attachment 7412 [details] Adds debugging spew to kernel to show frequency reduction
Further information about my configuration: The BIOS version is F.0D - the latest available from HP. My kernel options are ro root=LABEL=/ no_timer_check=0 rhgb quiet enforcing=0 noapic nolapic (no_timer_check, noapic, nolapic are there to work around various other - apparently independent - bugs relating to the HP NX6125).
Peter, do you still have this problem with 2.6.21?
I haven't seen this problem for some time, so I would say it is fixed in 2.6.21.
Thanks for reporting. Closing.