4 ms·
FreeBSD has powerd, it works with P-states. You can also write to MSRs with cpucontrol(8), I think CPUs use that to adjust clock and voltage from the OS.
by floatboth 9y ago
FreeBSD has powerd, it works with P-states. You can also write to MSRs with cpucontrol(8), I think CPUs use that to adjust clock and voltage from the OS.
- onli 9y agoUnder Linux, P-states are for Intel Core processors I think, but I do mean older than that. Pentium M. Maybe that's just not the case under BSD, or a mixup in terminology. cpucontrol could work here (but wow, that's raw). There seems to have been efforts to support it on other BSDs, https://mail-index.netbsd.org/tech-kern/2007/04/14/0003.html https://mail-index.netbsd.org/tech-kern/2007/04/14/0003.html and http://www.daemonology.net/freebsd-est/ http://www.daemonology.net/freebsd-est/ mentions the voltage (but it does not seem to be configurable, and if I got it right, this later became powerd). From what I could gather one could use cpucontrol to change the stored voltages and then let powerd, powerd++ or however OpenBSD handles this do its work. Thanks for that. But it looks like no one ever tried and reported on this. Hm.