Baremetal app time measurement using HWlib seems not accurate

Hi,

I'm using the Intel HWlib for measuring some steps execution time on the Arrive V SoC HPS (Arm CPU).

The problem is that I'm suspecting for getting unrealistic results.

The code is as follows:

1. /* Initialize and start timer (counter) for 9 seconds */

socfpga_timer_start(ALT_GPT_CPU_PRIVATE_TMR, 9000);

2. 10 Iterations loop:

2.1. /* get current counter value */

counter_val = alt_gpt_counter_get(ALT_GPT_CPU_PRIVATE_TMR);

2.2. /* 1 second delay */

alt_gpt_delay_ns(ALT_GPT_CPU_PRIVATE_TMR, counter_val, 1000000000)

2.3. /* start measure time */

start_time = alt_gpt_curtime_microsecs_get(ALT_GPT_CPU_PRIVATE_TMR);

2.4. /* perform step1 calculations */

.

.

2.5 /* stop measure time */

end_time = alt_gpt_curtime_microsecs_get(ALT_GPT_CPU_PRIVATE_TMR);

2.6. /* calculate step 1 execution time */

printf("\n elapsed time = %" PRIu32 "microsec\n" , t_start-t_end);

3.1. /* start measure time */

start_time = alt_gpt_curtime_microsecs_get(ALT_GPT_CPU_PRIVATE_TMR);

3.2. /* perform step2 calculations */

.

.

3.3 /* stop measure time */

end_time = alt_gpt_curtime_microsecs_get(ALT_GPT_CPU_PRIVATE_TMR);

3.4. /* calculate step 2 execution time */

printf("\n elapsed time = %" PRIu32 "microsec\n" , t_start-t_end);

* The counter doesn't reach 0 during these measurments *

I fear that I'm getting too long results for each measurement. Is there something wrong with my code?

Thanks