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    SubjectRe: [PATCH] i386: Selectable Frequency of the Timer Interrupt
    On 7/15/05, Linus Torvalds <torvalds@osdl.org> wrote:
    >
    > On Fri, 15 Jul 2005, Jesper Juhl wrote:
    > >
    > > It's buggy, that I know. setting kernel_hz (the new boot parameter) to
    > > 250 causes my system clock to run at something like 4-5 times normal
    > > speed
    >
    > 4 times normal. You don't actually make the timer interrupt happen at
    > 250Hz, so the timer will be programmed to run at the full 1kHz.
    >
    Right, that's the basic problem. I increase jiffies at a higher rate
    but didn't slow the timer interrupt down at the same time.

    > You also need to actually change the LATCH define (in
    > include/linux/jiffies.h) to take this into account (there might be
    > something else too).
    >
    [...]
    > and you might be getting closer.
    >
    > Of course, you need to make sure that LATCH is used only after
    > jiffies_increment is set up. See "setup_pit_timer(void)" in
    > arch/i386/kernel/timers/timer_pit.c for more details.
    >

    Thank you for all the pointers and hints. This is a new area of code
    for me, so I'll need some time to poke around - the above helps a lot.
    Unfortunately I won't have any time to work on this today, but I'll
    see if I can get a working implementation together tomorrow.

    --
    Jesper Juhl <jesper.juhl@gmail.com>
    Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html
    Plain text mails only, please http://www.expita.com/nomime.html
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