Add more comments, make graph tracer and affinity optionnal

clock-res/src/clockres.c

@@ -25,6 +25,7 @@ typedef struct thread_param {
   int priority;
   int max_cycles;
   int enable_tracing;
+  int enable_affinity;
   uint64_t interval;
   uint64_t latency_threshold;
   thread_stat_t stat;
@@ -33,6 +34,7 @@ typedef struct thread_param {
 typedef struct main_param {
   int refresh_rate;
   int enable_tracing;
+  int enable_graph;
 } main_param_t;
 
 static void process_options(int argc, char *argv[], thread_param_t *param,
@@ -53,11 +55,13 @@ static void *timerthread(void *p) {
   thread_param_t *param = (thread_param_t *)p;
   thread_stat_t *stat = &param->stat;
 
+  if(param->enable_affinity) {
     // Set thread CPU affinity
     CPU_ZERO(&mask);
     CPU_SET(1, &mask);
     if (sched_setaffinity(0, sizeof(mask), &mask))
       printf("Could not set CPU affinity to CPU #1\n");
+  }
 
   // Set thread priority
   priority.sched_priority = param->priority;
@@ -67,16 +71,20 @@ static void *timerthread(void *p) {
   stat->max_res = 0;
   stat->min_res = UINT64_MAX;
 
+  // Start tracing
   if (param->enable_tracing) tracing(1);
 
+  // Measurement loop
   for (stat->nb_cycles = 0;; stat->nb_cycles++) {
     if (param->max_cycles && (stat->nb_cycles >= param->max_cycles)) break;
 
+    // Two successive clock measurement to determine clock_gettime latency
     clock_gettime(CLOCK_ID, &previous);
     clock_gettime(CLOCK_ID, &current);
 
     diff = calcdiff_ns(current, previous);
 
+    // If the latency hits the tracing threshold, stop tracing
     if (param->enable_tracing && (diff > param->latency_threshold)) {
       sprintf(time_measured_string, "Diff measured: %" PRIu64 "\n", diff);
       tracemark(time_measured_string);
@@ -88,6 +96,8 @@ static void *timerthread(void *p) {
       break;
     }
 
+    // Update the thread statistics, so that the non real-time
+    // thread can print it
     stat->max_res = max(stat->max_res, diff);
     stat->min_res = min(stat->min_res, diff);
 
@@ -111,14 +121,19 @@ int main(int argc, char *argv[]) {
   param.max_cycles = 100000;
   param.priority = 99;
   param.enable_tracing = 0;
+  param.enable_affinity = 0;
+
   main_param.enable_tracing = 0;
+  main_param.enable_graph = 0;
   main_param.refresh_rate = 10000;
 
+  // Process bash options
   process_options(argc, argv, &param, &main_param);
 
+  // Enable ftrace
   if (main_param.enable_tracing) {
     param.enable_tracing = 1;
-    setup_tracer();
+    setup_tracer(main_param.enable_graph);
   }
 
   usleep(10000);
@@ -149,7 +164,7 @@ int main(int argc, char *argv[]) {
 static void process_options(int argc, char *argv[], thread_param_t *param,
                             main_param_t *main_param) {
   for (;;) {
-    int c = getopt(argc, argv, "l:p:i:r:b:f");
+    int c = getopt(argc, argv, "l:p:i:r:f:ag");
 
     if (c == -1) break;
 
@@ -163,14 +178,18 @@ static void process_options(int argc, char *argv[], thread_param_t *param,
       case 'i':
         param->interval = atoi(optarg);
         break;
-      case 'b':
-        param->latency_threshold = atoi(optarg);
-        break;
       case 'r':
         main_param->refresh_rate = atoi(optarg);
         break;
       case 'f':
         main_param->enable_tracing = 1;
+        param->latency_threshold = atoi(optarg);
+        break;
+      case 'a':
+        param->enable_affinity = 1;
+        break;
+      case 'g':
+        main_param->enable_graph = 1;
         break;
       default:
         exit(EXIT_FAILURE);

clock-res/src/tracer.c

@@ -74,7 +74,7 @@ static void setkernvar(const char *name, char *value) {
     fprintf(stderr, "could not set %s to %s\n", name, value);
 }
 
-void setup_tracer(void) {
+void setup_tracer(int enable_graph) {
 
   char trace_path[MAX_PATH];
   char tracemark_path[MAX_PATH];
@@ -85,6 +85,9 @@ void setup_tracer(void) {
   fileprefix = debugfileprefix;
   // Clear old traces by setting tracer to nop first
   setkernvar("current_tracer", "nop");
+  if(enable_graph)
+    setkernvar("current_tracer", "function_graph");
+  else
     setkernvar("current_tracer", "function");
 
   // Open tracing_on file

clock-res/src/tracer.h

 #ifndef TRACER_H
 #define TRACER_H
 
-void setup_tracer(void);
+void setup_tracer(int enable_graph);
 void tracing(int on);
 void tracemark(char * s);