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Date:      Mon, 25 May 2009 22:28:10 +0100
From:      Bruce Cran <bruce@cran.org.uk>
To:        Peter Boosten <peter@boosten.org>
Cc:        Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl>, Scott Bennett <bennett@cs.niu.edu>, freebsd-questions@freebsd.org, utisoft@gmail.com, Yuri <yuri@rawbw.com>
Subject:   Re: How can this 'top' command output make sense? Load over 7 and total CPU use ~5%
Message-ID:  <20090525222810.57e96c4a@gluon.draftnet>
In-Reply-To: <29229B06-6098-4488-9E9A-A5CFE6F9643B@boosten.org>
References:  <200905241315.n4ODFB96007801@mp.cs.niu.edu> <alpine.BSF.2.00.0905242021440.33060@wojtek.tensor.gdynia.pl> <b79ecaef0905250104p55c302cdh102202d1a06a389b@mail.gmail.com> <alpine.BSF.2.00.0905251013500.36458@wojtek.tensor.gdynia.pl> <b79ecaef0905250133n5cd641dv6ca8e088f8fa2f33@mail.gmail.com> <4A1A58FA.60303@boosten.org> <alpine.BSF.2.00.0905251912000.40022@wojtek.tensor.gdynia.pl> <C9B964A3-BE91-4518-B13C-EE28282FD810@boosten.org> <alpine.BSF.2.00.0905252107590.40989@wojtek.tensor.gdynia.pl> <1932D812-03CF-48AF-A306-669C39862EB7@boosten.org> <alpine.BSF.2.00.0905252119520.41069@wojtek.tensor.gdynia.pl> <EEB4E0E6-E903-4FCD-A583-2A17ACE9E902@boosten.org> <alpine.BSF.2.00.0905252135050.41170@wojtek.tensor.gdynia.pl> <29229B06-6098-4488-9E9A-A5CFE6F9643B@boosten.org>

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On Mon, 25 May 2009 21:42:40 +0200
Peter Boosten <peter@boosten.org> wrote:

> 
> On 25 mei 2009, at 21:37, Wojciech Puchar wrote:
> 
> >> The CPU = "Central Processing Unit" will perform it's
> >> calculations at so many megahertz while at 10% utilization or at
> >> 100% utilization. The entire machine
> >
> > no. it will not. all today x86 CPUs reacts on HLT command and  
> > doesn't do anything except waiting for interrupt (and saving lots
> > of power).
> >
> 
> Do you actually read back what you write: you're saying here that
> when a CPU has only 10% utilization, it'll run slower than when
> performing at 100%...

While it's not the default behaviour, if you run powerd(8) then
yes, the CPU will run slower when it's less utilized. 
My laptop will run at between 150MHz and 2500MHz depending on the
current workload.

-- 
Bruce Cran



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