Add minimum latency measurement

latency-measure/src/main.c

@@ -16,6 +16,7 @@
 typedef struct thread_stat {
   int nb_cycles;
   int64_t max_diff;
+  int64_t min_diff;
 } thread_stat_t;
 
 typedef struct thread_param {
@@ -41,6 +42,9 @@ static inline int64_t diff_ns(struct timespec t1, struct timespec t2) {
 static inline int64_t max(int64_t a, int64_t b) {
   return a > b ? a : b;
 }
+static inline int64_t min(int64_t a, int64_t b) {
+  return a < b ? a : b;
+}
 
 static inline struct timespec add_ns(struct timespec t, int64_t ns) {
   struct timespec ret;
@@ -75,6 +79,7 @@ static void *timerthread(void *p) {
     error(EXIT_FAILURE, errno, "Couldn't set priority");
 
   stat->max_diff = 0;
+  stat->min_diff = 1000000;
 
   clock_gettime(CLOCK_ID, &next);
   next = add_ns(next, param->interval);
@@ -88,7 +93,10 @@ static void *timerthread(void *p) {
     clock_nanosleep(CLOCK_ID, TIMER_ABSTIME, &next, NULL);
     clock_gettime(CLOCK_ID, &current);
 
-    stat->max_diff = max(stat->max_diff, diff_ns(current, next));
+    int64_t diff = diff_ns(current, next);
+
+    stat->max_diff = max(stat->max_diff, diff);
+    stat->min_diff = min(stat->min_diff, diff);
     
     next = add_ns(current, param->interval);
   }
@@ -144,13 +152,14 @@ int main(int argc, char *argv[]) {
 
   process_options(argc, argv, &param, &main_param);
 
-  sleep(3);
+  sleep(1);
 
   pthread_create(&thread, NULL, timerthread, (void *)&param);
 
   sleep(10);
 
   printf("Maximum latency: %" PRIi64 "us (%d)\n", (param.stat.max_diff / 1000), param.stat.nb_cycles);
+  printf("Minimum latency: %" PRIi64 "us (%d)\n", (param.stat.min_diff / 1000), param.stat.nb_cycles);
 
   //if(err)
   //  error(EXIT_FAILURE, errno, "Couldn't create thread");