[Bug 202140] HP Z600 defaults to LAPIC for kern.eventtimer.timer but can't use 'Online CPU idle state' higher than C1 with this setting
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Thu Aug 6 18:15:30 UTC 2015
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=202140
Bug ID: 202140
Summary: HP Z600 defaults to LAPIC for kern.eventtimer.timer
but can't use 'Online CPU idle state' higher than C1
with this setting
Product: Base System
Version: 10.1-STABLE
Hardware: amd64
OS: Any
Status: New
Severity: Affects Only Me
Priority: ---
Component: kern
Assignee: freebsd-bugs at FreeBSD.org
Reporter: brejoc at gmail.com
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)
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