ardupilot/ArduCopter/perf_info.cpp

#include "Copter.h"

//
//  high level performance monitoring
//
//  we measure the main loop time
//

// 400hz loop update rate
#define PERF_INFO_OVERTIME_THRESHOLD_MICROS 3000

static uint16_t perf_info_loop_count;
static uint32_t perf_info_max_time; // in microseconds
static uint32_t perf_info_min_time; // in microseconds
static uint64_t perf_info_sigma_time;
static uint64_t perf_info_sigmasquared_time;
static uint16_t perf_info_long_running;
static uint32_t perf_info_log_dropped;
static bool perf_ignore_loop = false;

// perf_info_reset - reset all records of loop time to zero
void Copter::perf_info_reset()
{
    perf_info_loop_count = 0;
    perf_info_max_time = 0;
    perf_info_min_time = 0;
    perf_info_long_running = 0;
    perf_info_log_dropped = DataFlash.num_dropped();
    perf_info_sigma_time = 0;
    perf_info_sigmasquared_time = 0;
}

// perf_ignore_loop - ignore this loop from performance measurements (used to reduce false positive when arming)
void Copter::perf_ignore_this_loop()
{
    perf_ignore_loop = true;
}

// perf_info_check_loop_time - check latest loop time vs min, max and overtime threshold
void Copter::perf_info_check_loop_time(uint32_t time_in_micros)
{
    perf_info_loop_count++;

    // exit if this loop should be ignored
    if (perf_ignore_loop) {
        perf_ignore_loop = false;
        return;
    }

    if( time_in_micros > perf_info_max_time) {
        perf_info_max_time = time_in_micros;
    }
    if( perf_info_min_time == 0 || time_in_micros < perf_info_min_time) {
        perf_info_min_time = time_in_micros;
    }
    if( time_in_micros > PERF_INFO_OVERTIME_THRESHOLD_MICROS ) {
        perf_info_long_running++;
    }
    perf_info_sigma_time += time_in_micros;
    perf_info_sigmasquared_time += time_in_micros * time_in_micros;
}

// perf_info_get_long_running_percentage - get number of long running loops as a percentage of the total number of loops
uint16_t Copter::perf_info_get_num_loops()
{
    return perf_info_loop_count;
}

// perf_info_get_max_time - return maximum loop time (in microseconds)
uint32_t Copter::perf_info_get_max_time()
{
    return perf_info_max_time;
}

// perf_info_get_max_time - return maximum loop time (in microseconds)
uint32_t Copter::perf_info_get_min_time()
{
    return perf_info_min_time;
}

// perf_info_get_num_long_running - get number of long running loops
uint16_t Copter::perf_info_get_num_long_running()
{
    return perf_info_long_running;
}

// perf_info_get_num_dropped - get number of dropped log messages
uint32_t Copter::perf_info_get_num_dropped()
{
    return perf_info_log_dropped;
}

// perf_info_get_avg_time - return average loop time (in microseconds)
uint32_t Copter::perf_info_get_avg_time()
{
    return (perf_info_sigma_time / perf_info_loop_count);
}

// perf_info_get_stddev_time - return stddev of average loop time (in us)
uint32_t Copter::perf_info_get_stddev_time()
{
    return sqrt((perf_info_sigmasquared_time - (perf_info_sigma_time*perf_info_sigma_time)/perf_info_loop_count) / perf_info_loop_count);
}