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    From
    SubjectRe: temperature standard - global config option?
    Date
    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.)

    -hpa
    --
    <hpa@transmeta.com> at work, <hpa@zytor.com> in private!
    "Unix gives you enough rope to shoot yourself in the foot."
    http://www.zytor.com/~hpa/puzzle.txt
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