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    SubjectRe: [PATCH] i386: Selectable Frequency of the Timer Interrupt


    On Thu, 14 Jul 2005, Vojtech Pavlik wrote:
    >
    > A note on the relaive timer API: There needs to be a way to say
    > "x milliseconds from the time this timer should have triggered" instead
    > of "x milliseconds from now", to avoid skew in timers that try to be
    > strictly periodic.

    I disagree.

    There should be an _absolute_ interface, and a driver that wants that
    should just have calculated when in time the timeout finishes - and then
    keep on using the absolute value.

    Btw, this is exactly why the jiffy-based thing is _good_. The kernel
    timers _are_ absolute, and you make them relative by adding "jiffies".

    The fact is, the current timers are better than people give them credit
    for, and converting them away from a jiffies-based interface (to a
    usleep-like one) is STUPID.

    There's absolutely nothing wrong with "jiffies", and anybody who thinks
    that

    msleep(20);

    is fundamentally better than

    timeout = jiffies + HZ/50;

    just doesn't realize that the latter is a bit more complicated exactly
    because the latter is a hell of a lot more POWERFUL. Trying to get rid of
    jiffies for some religious reason is _stupid_.

    I have to say, this whole thread has been pretty damn worthless in general
    in my not-so-humble opinion.

    Linus
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