(Follow-up from previous comment) I've done a closer study of my Dell X1 and as far as the Dell X1 is concerned (and may be true for others as well), this issue is definitely related to cpu heat. The X1 is an underpowered (1100MHz) Pentium M with purely passive cooling (no fan), so heat is a critical element.
Something in Linux is setting my heat ceiling at 65C. When the computer has a lot of work to do, powernowd sets the clock to full speed (1.1GHz) and the temperature slowly creeps up to 65C. When it reaches 65, the computer throttles down to 800MHz. This speed value is written into /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq, and so powernowd has only 600MHz and 800MHz to choose between. Even so, at 800MHz the computer will still creep up to 65C, and so when it reaches this temp, it will throttle down to 600MHz only. The problem is that normal operation doesn't return to the system until the CPU temp falls below the lower bound of 50C. That is, I can't get 800MHz or 1100MHz speeds until the processor is much cooler. Back in my EE days, we called this difference bewteen activation and disactivation a "hysteresis". A delta-Temp (or hysteresis) of 15C on this system is too high. So. I have identified two problems: 1. Thermal Threshold is set too low (this computer should run up to 70C (as it used to do under Feisty, kernel 2.6.16). 2. Hysteresis (that is, Delta-Temp) is set too wide...should be reduced to 5C or 7C, so that the computer can throttle up and throttle down. I don't know how to set/change any of these values. Any help out there? Thanks. -- cpufreq locked in slowest speed https://bugs.launchpad.net/bugs/88899 You received this bug notification because you are a member of Ubuntu Bugs, which is the bug contact for Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
