nios 2 - profiler Опции

[bool]

Помогите плиз разобраться с Performance Counter Core! В чём разница, почему в одном случае количество клоков насчитанных счётчиком 36 а в другом - 24, операции между PERF_BEGIN и PERF_END остаются те же

1)-------------------------------------------------------------------------------------------------------------------------------------

int main(void)
{
int a = 10, b = 20, c;
static int led = 0;

PERF_RESET(PERFORMANCE_COUNTER_BASE);
PERF_START_MEASURING(PERFORMANCE_COUNTER_BASE);
while(m<1000)
{
PERF_BEGIN(PERFORMANCE_COUNTER_BASE,1);
c = a*b;
led = led^0xFFFF;
IOWR_ALTERA_AVALON_PIO_DATA(PIO_2_BASE, led);
PERF_END(PERFORMANCE_COUNTER_BASE,1);
m++;
break;
}
PERF_STOP_MEASURING(PERFORMANCE_COUNTER_BASE);
perf_print_formatted_report( (void *)PERFORMANCE_COUNTER_BASE,
alt_get_cpu_freq(),
1,
"section #1"
);
return 0;
}


--Performance Counter Report--
Total Time: 1E-06 seconds (150 clock-cycles)
+---------------+-----+------------+----------------+--------------+
| Section | % | Time (sec)| Time (clocks)|Occurrences|
+---------------+-----+------------+----------------+--------------+
|section #1 | 24 | 0.00000| 36 | 1 |
+---------------+-----+------------+----------------+--------------+

2)--------------------------------------------------------------------------------------------------------------------------------------

nt main(void)
{
int a = 10, b = 20, c;
static int led = 0;

PERF_RESET(PERFORMANCE_COUNTER_BASE);
PERF_START_MEASURING(PERFORMANCE_COUNTER_BASE);
while(m<1000)
{
PERF_BEGIN(PERFORMANCE_COUNTER_BASE,1);
c = a*b;
led = led^0xFFFF;
IOWR_ALTERA_AVALON_PIO_DATA(PIO_2_BASE, led);
PERF_END(PERFORMANCE_COUNTER_BASE,1);
m++;
//break;
}
PERF_STOP_MEASURING(PERFORMANCE_COUNTER_BASE);
perf_print_formatted_report( (void *)PERFORMANCE_COUNTER_BASE,
alt_get_cpu_freq(),
1,
"section #1"
);
return 0;
}


--Performance Counter Report--
Total Time: 0.000267507 seconds (40126 clock-cycles)
+---------------+-----+------------+----------------+--------------+
| Section | % | Time (sec)| Time (clocks)|Occurrences|
+---------------+-----+------------+----------------+--------------+
|section #1 | 59.8| 0.00016 | 24012 | 1000 |
+---------------+-----+------------+----------------+--------------+