Fwd: High Pitched Whine

Paul Lipps paul.lipps at gmail.com
Tue Jun 6 09:23:18 UTC 2006

Sorry, for some reason I thought I was going to have to build a new  

I set my HZ to 100 in the loader.conf, and it did lower the pitch of  
the whine to where I can hardly hear it now. I can still hear a  
difference when I toggle the CPU halt off and on, but the difference  
between 1000 and 100 HZ is like night and day.

Thank you very much, my ears appreciate it. :)

Paul Lipps
paul.lipps at gmail.com

Begin forwarded message:

> From: Paul Lipps <paul.lipps at gmail.com>
> Date: June 6, 2006 4:01:48 AM CDT
> To: Joseph Koshy <joseph.koshy at gmail.com>
> Cc: freebsd-smp at freebsd.org
> Subject: Re: High Pitched Whine
> On Jun 6, 2006, at 1:10 AM, Joseph Koshy wrote:
>> The only thing that I can think of that could think of that
>> could whine is a flaky magnetic component.
>> Does the frequency of the whine change if you change HZ?
>> Does the whine reduce if the processor is fully compute
>> bound?
> Yes, the whine actually goes away under a full load. It is  
> intermittent when the CPU is being stressed intermittently, and of  
> course constant when the CPU is idle.
> I am going to try compiling a new kernel with a reduced HZ setting  
> as suggested. Is the output of this command:
> sysctl kern.clockrate
> displaying the current HZ setting? If so it's 1000 at the moment. I  
> will compile a new kernel using the GENERIC configuration file with  
> only the HZ option changed to 100 rather then 1000 and report my  
> findings.

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