trace-cmd: Do not enable tracing until exec

Wait till the last moment to enable tracing. Otherwise we trace
the trace-cmd utility setting up the program and waste a lot of
the data file.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 21 insertions, 21 deletions

diff --git a/trace-cmd.c b/trace-cmd.c
index 75bc325..182c8d6 100644
--- a/trace-cmd.c
+++ b/trace-cmd.c
@@ -249,6 +249,21 @@ static void clear_trace(void)
         fclose(fp);
 }
 
+static void reset_max_latency(void)
+{
+        FILE *fp;
+        char *path;
+
+        /* reset the trace */
+        path = get_tracing_file("tracing_max_latency");
+        fp = fopen(path, "w");
+        if (!fp)
+                die("writing to '%s'", path);
+        put_tracing_file(path);
+        fwrite("0", 1, 1, fp);
+        fclose(fp);
+}
+
 static void update_ftrace_pid(const char *pid)
 {
         char *path;
@@ -269,6 +284,7 @@ static void update_ftrace_pid(const char *pid)
 }
 
 static void update_pid_event_filters(char *pid);
+static void enable_tracing(void);
 
 static void update_task_filter(void)
 {
@@ -277,6 +293,7 @@ static void update_task_filter(void)
 
         if (!filter_task) {
                 update_ftrace_pid("");
+                enable_tracing();
                 return;
         }
 
@@ -286,8 +303,7 @@ static void update_task_filter(void)
 
         update_pid_event_filters(spid);
 
-        /* clear the trace */
-
+        enable_tracing();
 }
 
 void run_cmd(int argc, char **argv)
@@ -717,6 +733,9 @@ static void write_tracing_on(int on)
 static void enable_tracing(void)
 {
         write_tracing_on(1);
+
+        if (latency)
+                reset_max_latency();
 }
 
 static void disable_tracing(void)
@@ -734,21 +753,6 @@ static void disable_all(void)
         clear_trace();
 }
 
-static void reset_max_latency(void)
-{
-        FILE *fp;
-        char *path;
-
-        /* reset the trace */
-        path = get_tracing_file("tracing_max_latency");
-        fp = fopen(path, "w");
-        if (!fp)
-                die("writing to '%s'", path);
-        put_tracing_file(path);
-        fwrite("0", 1, 1, fp);
-        fclose(fp);
-}
-
 static void update_pid_event_filters(char *pid)
 {
         struct event_list *event;
@@ -1246,10 +1250,6 @@ int main (int argc, char **argv)
                         sleep(1);
                 }
         } else {
-                enable_tracing();
-                if (latency)
-                        reset_max_latency();
-
                 if (!record)
                         exit(0);