Add trace marking

clock-res/src/clockres.c

@@ -59,17 +59,20 @@ static void *timerthread(void *p) {
   stat->max_res = 0;
   stat->min_res = UINT64_MAX;
 
+  if(param->enable_tracing)
+    tracing(1);
+
   for (stat->nb_cycles = 0;; stat->nb_cycles++) {
     if (param->max_cycles && (stat->nb_cycles >= param->max_cycles)) break;
 
     if(param->enable_tracing)
-      tracing(1);
+      tracemark("Time measure start\n");
 
     clock_gettime(CLOCK_ID, &previous);
     clock_gettime(CLOCK_ID, &current);
 
     if(param->enable_tracing)
-      tracing(0);
+      tracemark("Time measure end\n");
 
     diff = calcdiff_ns(current, previous);
 
@@ -81,6 +84,10 @@ static void *timerthread(void *p) {
     usleep(param->interval);
   }
 
+  if(param->enable_tracing)
+    tracing(0);
+
+
   return NULL;
 }
 
@@ -123,7 +130,9 @@ int main(int argc, char *argv[]) {
     if (main_param.enable_tracing && (param.stat.max_res >= param.latency_threshold)) break;
   }
 
-  tracing(0);
+  // Just in case main exists before the thread
+  if(main_param.enable_tracing)
+    tracing(0);
 
   exit(EXIT_SUCCESS);
 }

clock-res/src/tracer.c

@@ -39,7 +39,9 @@
 static char *fileprefix;
 static char *procfileprefix = "/proc/sys/kernel/";
 static char *debugfileprefix = "/sys/kernel/debug/tracing/";
+
 static int trace_fd = -1;
+static int tracemark_fd = -1;
 
 static int kernvar(int mode, const char *name, char *value,
                    size_t sizeofvalue) {
@@ -74,6 +76,9 @@ static void setkernvar(const char *name, char *value) {
 
 void setup_tracer(void) {
 
+  char trace_path[MAX_PATH];
+  char tracemark_path[MAX_PATH];
+
   fileprefix = procfileprefix;
   setkernvar("ftrace_enabled", "1");
 
@@ -82,14 +87,17 @@ void setup_tracer(void) {
   setkernvar("current_tracer", "nop");
   setkernvar("current_tracer", "function");
 
-  /* open the tracing on file descriptor */
-  if (trace_fd == -1) {
-    char path[MAX_PATH];
-    strcpy(path, fileprefix);
-    strcat(path, "tracing_on");
-    if ((trace_fd = open(path, O_WRONLY)) == -1)
-      printf("unable to open %s for tracing", path);
-  }
+  // Open tracing_on file
+  strcpy(trace_path, fileprefix);
+  strcat(trace_path, "tracing_on");
+  if ((trace_fd = open(trace_path, O_WRONLY)) == -1)
+    printf("unable to open %s for tracing", trace_path);
+
+  // Open trace mark file
+  strcpy(tracemark_path, fileprefix);
+  strcat(tracemark_path, "trace_marker");
+  if ((tracemark_fd = open(tracemark_path, O_WRONLY)) == -1)
+    printf("unable to open %s for tracing", tracemark_path);
 
   tracing(0);
 }
@@ -100,3 +108,7 @@ void tracing(int on) {
   else
     write(trace_fd, "0", 1);
 }
+
+void tracemark(char * s) {
+  write(tracemark_fd, s, strlen(s));
+}

clock-res/src/tracer.h

@@ -3,5 +3,6 @@
 
 void setup_tracer(void);
 void tracing(int on);
+void tracemark(char * s);
 
 #endif