idle process keeping cpu 150% busy in freebsd 9.1-amd64

[John Baldwin]

On Friday, May 31, 2013 10:47:34 am Kostas Oikonomou wrote:
> Thanks very much for the reply.
> 
> Being new to FreeBSD, this still seems weird to me.  (My 
> background is Solaris.)
> 
> On both machines, the core that's running at 150% in the 
> case of the HP machine, and at 400% in the case
> of the Dell laptop, is causing the fans to come on.  Would 
> you call that "idle"?  I'm worried that the cores will
> eventually be damaged.

Do you have deeper Cx states enabled?  By default FreeBSD will only enter C1.  
Try setting 'performance_cx_lowest=LOW' in /etc/rc.conf and either rebooting 
or running '/etc/rc.d/power_profile start' to see if that helps.  You can see 
which Cx states are being used by running 'sysctl dev.cpu | grep cx_'.  For 
example:

dev.cpu.0.cx_supported: C1/3 C2/59 C3/93
dev.cpu.0.cx_lowest: C1
dev.cpu.0.cx_usage: 100.00% 0.00% 0.00% last 324us
dev.cpu.1.cx_supported: C1/3 C2/59 C3/93
dev.cpu.1.cx_lowest: C1
dev.cpu.1.cx_usage: 100.00% 0.00% 0.00% last 300us
dev.cpu.2.cx_supported: C1/3 C2/59 C3/93
dev.cpu.2.cx_lowest: C1
dev.cpu.2.cx_usage: 100.00% 0.00% 0.00% last 192us
dev.cpu.3.cx_supported: C1/3 C2/59 C3/93
dev.cpu.3.cx_lowest: C1
dev.cpu.3.cx_usage: 100.00% 0.00% 0.00% last 157us

This is on a machine with the default setup.  After changing it to use the 
lowest setting:

dev.cpu.0.cx_supported: C1/3 C2/59 C3/93
dev.cpu.0.cx_lowest: C3
dev.cpu.0.cx_usage: 5.84% 92.86% 1.28% last 145us
dev.cpu.1.cx_supported: C1/3 C2/59 C3/93
dev.cpu.1.cx_lowest: C3
dev.cpu.1.cx_usage: 0.99% 94.92% 4.08% last 293us
dev.cpu.2.cx_supported: C1/3 C2/59 C3/93
dev.cpu.2.cx_lowest: C3
dev.cpu.2.cx_usage: 0.45% 88.50% 11.04% last 174us
dev.cpu.3.cx_supported: C1/3 C2/59 C3/93
dev.cpu.3.cx_lowest: C3
dev.cpu.3.cx_usage: 6.40% 86.89% 6.69% last 203us

Another option is to run powerd which will throttle your CPUs down to lower 
clock speeds when they are idle.  You can enable this by setting 
powerd_enable="YES" in /etc/rc.conf and running '/etc/rc.d/powerd start'.

-- 
John Baldwin