[bench.c] calculate used time

bench.c

@@ -7,6 +7,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <sys/eventfd.h>
+#include <sys/resource.h>
 
 #include "stats.h"
 #include "stopwatch.h"
@@ -19,6 +20,19 @@ unsigned iterations = 1000000;
 
 #define BUFSIZE 64
 
+// Calculate and return total time of this process in usec
+static uint64_t calc_proc_time(struct timeval *utime, struct timeval *stime) {
+	uint64_t t = utime->tv_sec * 1000 * 1000 + utime->tv_usec;
+	t += stime->tv_sec * 1000 * 1000 + stime->tv_usec;
+	return t;
+}
+
+static uint64_t get_proc_time() {
+	struct rusage r_usage;
+	getrusage(RUSAGE_SELF, &r_usage);
+	return calc_proc_time(&r_usage.ru_utime, &r_usage.ru_stime);
+}
+
 static int create_eventfd() {
 	int fd = eventfd(UINT_MAX, EFD_SEMAPHORE);
 	if (fd == -1) {
@@ -30,8 +44,7 @@ static int create_eventfd() {
 int main(int argc, char *argv[]) {
 	bool print_data = false;
 	bool print_stats = false;
-	if (argc > 2)
-		errx(EXIT_SUCCESS, "Usage: %s [--print-data]", argv[0]);
+	if (argc > 2) errx(EXIT_SUCCESS, "Usage: %s [--print-data]", argv[0]);
 
 	if (argc == 2) {
 		if ((strcmp(argv[1], "--print-data") == 0))
@@ -58,19 +71,23 @@ int main(int argc, char *argv[]) {
 
 	for (unsigned i = 0; i < exp_warmup; ++i) do_read(fd, &read_buf, sizeof(read_buf));
 
+	uint64_t proc_time_start = get_proc_time();
+
 	for (unsigned i = 1; i <= exp_iterations; ++i) {
 		do_read(fd, &read_buf, sizeof(read_buf));
 		nanos[i - 1] = clock_diff_nanos();
 		cycles[i - 1] = clock_diff_cycles();
 	}
+	uint64_t proc_time_end = get_proc_time();
+	uint64_t proc_time_used = proc_time_end - proc_time_start;
 
 	if (print_data) {
-		for (unsigned i = 0; i < exp_iterations; ++i)
-			printf("%lu,%lu\n", nanos[i], cycles[i]);
+		for (unsigned i = 0; i < exp_iterations; ++i) printf("%lu,%lu\n", nanos[i], cycles[i]);
 	} else if (print_stats) {
 		print_desc_stats("nanos", "  ", nanos, exp_iterations);
 		print_desc_stats("cycles", "  ", cycles, exp_iterations);
 	} else {
+		printf("time-spent: %lu usec ", proc_time_used);
 		uint64_t avg_nanos = calc_mean(nanos, exp_iterations);
 		uint64_t avg_cycles = calc_mean(cycles, exp_iterations);
 		printf("avg-nanos: %lu, avg-cycles: %lu\n", avg_nanos, avg_cycles);