This computer is comsuming 160 watt when idle. I was looking for a way to reduce that and was told to set 'hw.acpi.cpu.cx_lowest' to 'C3' or 'C8'. If I'm setting 'hw.acpi.cpu.cx_lowest' to anything else than 'C1' the system stops working properly. Applications just stop - waiting forever. This can very easily be reproduced with ping. Starting to type anything on the shell "wakes" the computer up and applications start to respond and work again. A clean reboot is not possible with these settings. Default for this computer for 'kern.eventtimer.timer' is 'LAPIC'. Allan Jude from BSD Now, who was guiding me through the whole process, told me to try 'HPET', which worked. Both 'C3' and 'C8' for 'hw.acpi.cpu.cx_lowest' are now possible without any downside effects. Power consumption is down to around 90 watt with 'C8' and the system is working flawlessly and stable. Thanks Allan, Kris and last but not least TJ! But it would be much nicer, if this would work right out of the box! Some additional information: --- Xeon E5520 --- $ sysctl hw.|head hw.machine: amd64 hw.model: Intel(R) Xeon(R) CPU E5520 @ 2.27GHz hw.ncpu: 8 hw.byteorder: 1234 hw.physmem: 8545079296 hw.usermem: 8300666880 hw.pagesize: 4096 hw.floatingpoint: 1 hw.machine_arch: amd64 hw.realmem: 8592031744 --- Event timer choices --- $ sysctl kern.eventtimer.choice kern.eventtimer.choice: LAPIC(400) HPET(350) HPET1(340) HPET2(340) HPET3(340) i8254(100) RTC(0)
I'm now having exactly the same problem with an older Samsung NC10 - a so called netbook. 'kern.eventtimer.timer' defaults to 'HPET'. But in this case the solution seems to be 'LAPIC'. --- Event timer choices --- $ sysctl kern.eventtimer.choice kern.eventtimer.choice: HPET(450) HPET1(440) HPET2(440) LAPIC(400) i8254(100) RTC(0) --- Intel Atom CPU N270 --- $ sysctl hw.|head hw.machine: i386 hw.model: Intel(R) Atom(TM) CPU N270 @ 1.60GHz hw.ncpu: 2 hw.byteorder: 1234 hw.physmem: 1042579456 hw.usermem: 920571904 hw.pagesize: 4096 hw.floatingpoint: 1 hw.machine_arch: i386 hw.realmem: 1073741824
Hello. Have you tried using these instructions completely? https://wiki.freebsd.org/TuningPowerConsumption
Hi Ivan, changing the timer solves the problem. But if those timers can't be used with C8, perhaps they shouldn't be the default in the first place.