publish sleeptest.c tool

src/tools/sleeptest.c

@@ -0,0 +1,58 @@
+
+#include <time.h>
+#include <sys/time.h>
+#include <stdio.h>
+#include <unistd.h>
+
+static double timeval_diff(struct timeval start, struct timeval end)
+{
+	double diff;
+	
+	diff = (end.tv_sec - start.tv_sec)
+		+ ((end.tv_usec - start.tv_usec) / 1000000.0);
+	
+	return diff;
+}
+
+
+int main(int argc, char **argv)
+{
+	time_t tick;
+	time_t previous_tick;
+	struct timespec sleep_req;
+	struct timeval sleep_start, sleep_end;
+	struct tm lt;
+	
+	time(&previous_tick);
+	
+	sleep_req.tv_sec = 0;
+	sleep_req.tv_nsec = 210 * 1000 * 1000; /* 210 ms */
+	
+	while (1) {
+		gettimeofday(&sleep_start, NULL);
+		nanosleep(&sleep_req, NULL);
+		gettimeofday(&sleep_end, NULL);
+		time(&tick);
+		gmtime_r(&sleep_start.tv_sec, &lt);
+		
+		double slept = timeval_diff(sleep_start, sleep_end);
+		if (slept > 0.50) {
+			printf("%4d/%02d/%02d %02d:%02d:%02d.%06d ", lt.tm_year + 1900, lt.tm_mon + 1, lt.tm_mday, lt.tm_hour, lt.tm_min, lt.tm_sec, (int)sleep_start.tv_usec);
+			printf("time keeping: sleep of %ld ms took %.6f s!\n", sleep_req.tv_nsec / 1000 / 1000, slept);
+		}
+		
+		/* catch some oddities with time keeping */
+		if (tick != previous_tick) {
+			if (previous_tick > tick) {
+				printf("%4d/%02d/%02d %02d:%02d:%02d.%06d ", lt.tm_year + 1900, lt.tm_mon + 1, lt.tm_mday, lt.tm_hour, lt.tm_min, lt.tm_sec, (int)sleep_start.tv_usec);
+				printf("time keeping: Time jumped backward by %ld seconds!\n", previous_tick - tick);
+			} else if (previous_tick < tick-1) {
+				printf("%4d/%02d/%02d %02d:%02d:%02d.%06d ", lt.tm_year + 1900, lt.tm_mon + 1, lt.tm_mday, lt.tm_hour, lt.tm_min, lt.tm_sec, (int)sleep_start.tv_usec);
+				printf("time keeping: Time jumped forward by %ld seconds!\n", tick - previous_tick);
+			}
+			
+			previous_tick = tick;
+		}
+		
+	}
+}