Date: Fri, 18 Jan 2008 10:36:09 +0100 From: =?utf-8?Q?Dag-Erling_Sm=C3=B8rgrav?= <des@des.no> To: Nate Lawson <nate@root.org> Cc: freebsd-current@freebsd.org, Maxim Sobolev <sobomax@digifonica.com>, Igor Mozolevsky <igor@hybrid-lab.co.uk>, Stefan Lambrev <stefan.lambrev@moneybookers.com> Subject: Re: powerd adaptive mode latching Message-ID: <86y7aneara.fsf@ds4.des.no> In-Reply-To: <478F8A75.5010701@root.org> (Nate Lawson's message of "Thu\, 17 Jan 2008 09\:03\:49 -0800") References: <a2b6592c0801110351l382959ffh1d55f2bcd2e6ca1b@mail.gmail.com> <a2b6592c0801111119r148d3697hf75a59b7bf74d540@mail.gmail.com> <478930D2.90806@digifonica.com> <200801171115.43663.doconnor@gsoft.com.au> <86myr4n4gp.fsf@ds4.des.no> <478F8A75.5010701@root.org>
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Nate Lawson <nate@root.org> writes: > Dag-Erling Sm=C3=B8rgrav <des@des.no> writes: > > [powerd's load calculation] is based on the (didle/dt) / (dtotal/dt) > > fraction computed from kern.cp_time, which can take a while to ramp > > up. This is not easily seen in a cursory reading of the code, as the > > fraction is computed in a very roundabout way. > While providing more accurate information to powerd is a good goal, I > want to preempt any requests to move the scheduling algorithm into the > kernel. Never struck my mind. Policy belongs in userland. However, the load calculations could benefit from a (semantically identical) rewrite, if only to make them more easily understandable to the reader. I would rename a couple of variables to make it clear that they are derivatives, compute the fraction explicitly, and use an internal representation of the threshold that places it in [0..1] instead of [0..100], allowing a direct comparison. DES --=20 Dag-Erling Sm=C3=B8rgrav - des@des.no
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