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    SubjectRe: time warps, I despair

    could you please try out this modified version of pentium_timer_interrput:

    static void pentium_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
    unsigned long long saved_timer_cc = 0;
    /* code to identify LARGE interrupt delays ... testing only */


    /* read Pentium cycle counter */
    __asm__(".byte 0x0f,0x31"
    :"=a" (last_timer_cc.low),
    "=d" (last_timer_cc.high));

    if ( last_timer_cc-saved_timer_cc > CYCLES_PER_JIFFY/3 )
    printk("ayyee, IRQ delay bigger than 1/3 jiffy: %Lu.\n",
    last_timer-saved_timer );

    saved_timer_cc = last_timer_cc;
    timer_interrupt(irq, NULL, regs);

    actually i havent even checked if it compiles. Note that you have to
    define CPU_INTERNAL_SPEED_IN_MHZ 133 if you have a 133 MHz machine.

    this code identifies lost jiffies >for sure<, provided that the lost
    jiffy is 'casual', and not a systematic delay of timer interrupts. [the
    latter could be only caused by pathetic load, which is not the case in
    your situation].


    ps. printk-ing in the timer interrupt isnt exactly pretty, but we are
    doomed at that point anyways, so the printk at least wont >cause< a lost
    jiffy :)

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      Last update: 2005-03-22 13:37    [W:0.017 / U:0.992 seconds]
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