Messages in this thread | | | From | "H. Peter Anvin" <> | Subject | Re: temperature standard - global config option? | Date | 9 Jun 2001 00:55:42 -0700 |
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Followup to: <B7471019.F9CF%bootc@worldnet.fr> By author: Chris Boot <bootc@worldnet.fr> In newsgroup: linux.dev.kernel > > Well then, tell all the teachers in this world that they're stupid, and tell > everyone who learnt from them as well. I'm in high school (gd. 11, junior) > and my physics teacher is always screaming at us for putting too many > decimal places or having them inconsistent. There are certain situations > where adding a ±1 is too cumbersome and / or clumsy, so you can specify the > accuracy using just decimal places. >
This, again, is a presentation issue, and is irrelevant to the intricacies of fixed-point arithmetric.
> For example, 5.00 would mean pretty much spot on 5 (anywhere from 4.995 to > 5.00499), wheras 5 could mean anywhere from 4.5 to 5.499. > > Please, let's quit this dumb argument. We all know that thermistors and > other types of cheap temperature gauges are very inaccurate, and I don't > think expensive thermocouples will make it into computer sensors very soon. > Plus, who the hell could care whether their chip is at 45.4 or 45.5 degrees? > Does it really matter? A difference of 0.1 will not decide whether your > chip will fry.
Does it really matter NOW? No. However, 1 cK is a convenient unit and a good use of bits. Can we guarantee it won't matter in the future, especially not on a CPU which may very well require complex algorithms to eke out optimal performance in a thermally-challenged environment (more than just simple trip points.) Now it gets interesting! I have actually seen, in the lab, an algorithm which required complex guesswork, because it required information below the noise level of the sensor (and yes, it *is* possible to obtain that information.)
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