test_overhead.c

/**
 * Overhead Test - Measures the profiler's performance overhead
 */

#include "profiler.h"
#include <stdio.h>

#define ITERATIONS 1000000

int main(void) {
    profiler_init();
    
    printf("=== Profiler Overhead Test ===\n\n");
    
    /* Measure timer start/stop overhead */
    profiler_timer_t overhead_timer;
    profiler_timer_start(&overhead_timer, "overhead_measurement");
    
    for (int i = 0; i < ITERATIONS; i++) {
        profiler_timer_t t;
        profiler_timer_start(&t, "test");
        profiler_timer_stop(&t);
    }
    
    profiler_timer_stop(&overhead_timer);
    
    uint64_t total_ns = profiler_timer_elapsed_ns(&overhead_timer);
    double per_operation_ns = total_ns > 0 ? 
        (double)total_ns / (double)ITERATIONS : 0.0;
    
    printf("Total iterations: %d\n", ITERATIONS);
    printf("Total time: %.3f ms\n", profiler_timer_elapsed_ms(&overhead_timer));
    printf("Average overhead per start/stop: %.1f ns\n", per_operation_ns);
    
    /* Test disabled profiler overhead */
    profiler_enable(false);
    
    profiler_timer_t disabled_timer;
    profiler_timer_start(&disabled_timer, "disabled_measurement");
    
    for (int i = 0; i < ITERATIONS; i++) {
        profiler_timer_t t;
        profiler_timer_start(&t, "test");
        profiler_timer_stop(&t);
    }
    
    profiler_timer_stop(&disabled_timer);
    
    /* Enable to print results */
    profiler_enable(true);
    
    printf("\nWith profiling disabled:\n");
    printf("Total time: %.3f ms\n", profiler_timer_elapsed_ms(&disabled_timer));
    
    uint64_t overhead_ns = profiler_timer_elapsed_ns(&overhead_timer);
    uint64_t disabled_ns = profiler_timer_elapsed_ns(&disabled_timer);
    
    if (overhead_ns > 0) {
        printf("Overhead reduction: %.1f%%\n", 
               100.0 * (1.0 - (double)disabled_ns / (double)overhead_ns));
    }
    
    profiler_shutdown();
    return 0;
}