[ECOS] a qustion about measure real-time interrupt latency

[ECOS] a qustion about measure real-time interrupt latency

[xuas]

I cant understand something about isr doing.
can someone help me ?

what is mean measure real-time interrupt latency?
what is aim?

 
the isr code is:
 
cyg_uint32 Cyg_RealTimeClock::isr(cyg_vector vector, CYG_ADDRWORD data)
{
#if defined(CYGVAR_KERNEL_COUNTERS_CLOCK_LATENCY) && defined(HAL_CLOCK_LATENCY)
    if (measure_clock_latency) {
        cyg_int32 delta;
        HAL_CLOCK_LATENCY(&delta);
        // Note: Ignore a latency of 0 when finding min_clock_latency.
        if (delta > 0) {
            // Valid delta measured
            total_clock_latency += delta;
            total_clock_interrupts++;
            if (min_clock_latency > delta) min_clock_latency = delta;
            if (max_clock_latency < delta) max_clock_latency = delta;
        }
    }
#endif

    CYG_INSTRUMENT_CLOCK( ISR, 0, 0);

    HAL_CLOCK_RESET( CYGNUM_HAL_INTERRUPT_RTC, CYGNUM_KERNEL_COUNTERS_RTC_PERIOD );

    Cyg_Interrupt::acknowledge_interrupt(CYGNUM_HAL_INTERRUPT_RTC);

#if defined(CYGVAR_KERNEL_COUNTERS_CLOCK_DSR_LATENCY)
    HAL_CLOCK_READ(&clock_dsr_start);
#endif    
    return Cyg_Interrupt::CALL_DSR|Cyg_Interrupt::HANDLED;
}

Re: [ECOS] a qustion about measure real-time interrupt latency

[Jonathan Larmour]

xuas wrote:
> 
> I cant understand something about isr doing.
> can someone help me ?
> 
> what is mean measure real-time interrupt latency?
> what is aim?

It's there purely to, um...,  measure the latency. It's purely for
information purposes that's all. The kernel tm_basic test takes advantage
of it for example... if you enable this option, it will report the
interrupt (and DSR if also enabled) latency for the clock interrupt and
tell you what it is, purely for your information.

Jifl
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