On Mon, Jan 13, 2014 at 4:10 AM, Juan Francisco Cantero Hurtado <i...@juanfra.info> wrote: > On Sun, Jan 12, 2014 at 05:29:02PM +0100, John Rogers wrote: >> Hi. >> >> I have installed OpenBSD 5.4 on a laptop. So far everything runs fine >> but I have the problem that it runs fairly hot even in idle. >> >> I used to run FreeBSD on it before and it behaved very similar then, >> until I read [1]. Setting performance_cx_lowest="C2" and >> economy_cx_lowest="C2" did wonder to this machine and effectively >> lowered the temperature and fan speed to acceptable levels. My >> understanding is that this uses ACPI to make the processor run in at >> least C2 state which makes it wake up somewhat slower but in general >> decreases power usage. >> >> My question is if I can do something similar with OpenBSD. I've read >> through the source code to acpicpu(4) [2] and it mentions c-states >> here and there, but I'm not used to the OpenBSD kernel source code and >> is unable to tell how I can utilize it. >> >> John >> >> >> [1] https://wiki.freebsd.org/TuningPowerConsumption >> [2] http://www.openbsd.org/cgi-bin/cvsweb/src/sys/dev/acpi/acpicpu.c?rev=HEAD >> > > Try apmd(8).
Thanks for the suggestion. I have added apmd_flags="-C" to /etc/rc.conf.local. It looks like it has some effect on the machine but it is still running at much higher temperature in idle compared to what is normal for it. I'm not an expert on this but my theory is that the problem is not that the CPU is running too fast but rather that it is running in a high power state, presumably C0. Do you know if apmd adjusts the c-state? John
