Date: Tue, 06 Jun 2006 22:17:58 +0800 From: Julian Elischer <julian@elischer.org> To: Paul Lipps <paul.lipps@gmail.com> Cc: freebsd-smp@freebsd.org, Joseph Koshy <joseph.koshy@gmail.com> Subject: Re: High Pitched Whine Message-ID: <44858E96.1000500@elischer.org> In-Reply-To: <4BA3465C-BEAD-4DAE-8975-804BB8EB25E6@gmail.com> References: <988CE3F0-B4FB-40B3-AE6E-C079E54BD290@gmail.com> <84dead720606052310s62ad2a5dt884fce4dd192b05d@mail.gmail.com> <4BA3465C-BEAD-4DAE-8975-804BB8EB25E6@gmail.com>
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Paul Lipps wrote: > 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. > > > > _______________________________________________ > freebsd-smp@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-smp > To unsubscribe, send any mail to "freebsd-smp-unsubscribe@freebsd.org" The whine is probably coming from an element in the power supply. The hlt systctl that you mention allows the processor to halt when not in use and only wake up when busy or at interrupts (minimum of 'hz' times per second) A halt state uses a lot less power so the current load goes up and down with a 1kHz base and some random variance. When loaded this can not be heard because the current is more ccontinuous.
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