instrumentation sched: add missing fork pid info

Fixes #434

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/instrumentation/events/lttng-module/sched.h b/instrumentation/events/lttng-module/sched.h
index 4d30fe3e1acbb2eb74bff3e2f9c64db1a31fa788..e42acd23f23cd8761c8daa7a800cfab72a62ccfe 100644 (file)
--- a/instrumentation/events/lttng-module/sched.h
+++ b/instrumentation/events/lttng-module/sched.h
@@ -327,7 +327,12 @@ TRACE_EVENT(sched_process_wait,
 )
 
 /*
- * Tracepoint for do_fork:
+ * Tracepoint for do_fork.
+ * Saving both TID and PID information, especially for the child, allows
+ * trace analyzers to distinguish between creation of a new process and
+ * creation of a new thread. Newly created processes will have child_tid
+ * == child_pid, while creation of a thread yields to child_tid !=
+ * child_pid.
  */
 TRACE_EVENT(sched_process_fork,
 
@@ -338,15 +343,19 @@ TRACE_EVENT(sched_process_fork,
        TP_STRUCT__entry(
                __array_text(   char,   parent_comm,    TASK_COMM_LEN   )
                __field(        pid_t,  parent_tid                      )
+               __field(        pid_t,  parent_pid                      )
                __array_text(   char,   child_comm,     TASK_COMM_LEN   )
                __field(        pid_t,  child_tid                       )
+               __field(        pid_t,  child_pid                       )
        ),
 
        TP_fast_assign(
                tp_memcpy(parent_comm, parent->comm, TASK_COMM_LEN)
                tp_assign(parent_tid, parent->pid)
+               tp_assign(parent_pid, parent->tgid)
                tp_memcpy(child_comm, child->comm, TASK_COMM_LEN)
                tp_assign(child_tid, child->pid)
+               tp_assign(child_pid, child->tgid)
        ),
 
        TP_printk("comm=%s tid=%d child_comm=%s child_tid=%d",