Define the task-tracking events

Based on initial patches by Mikolaj Konarski <mikolaj@well-typed.com>

These new eventlog events are to let profiling tools keep track of all
the OS threads that belong to an RTS capability at any moment in time.
In the RTS, OS threads correspond to the Task abstraction, so that is
what we track. There are events for tasks being created, migrated
between capabilities and deleted. In particular the task creation event
also records the kernel thread id which lets us match up the OS thread
with data collected by others tools (in the initial use case with
Linux's perf tool, but in principle also with DTrace).

1 files changed, 46 insertions, 0 deletions

diff --git a/rts/Trace.c b/rts/Trace.c
index 9fa8eb177b..a946f2c5d3 100644
--- a/rts/Trace.c
+++ b/rts/Trace.c
@@ -574,6 +574,52 @@ void traceSparkCounters_ (Capability *cap,
     }
 }
 
+void traceTaskCreate_ (Task       *task,
+                       Capability *cap)
+{
+#ifdef DEBUG
+    if (RtsFlags.TraceFlags.tracing == TRACE_STDERR) {
+        /* We currently don't do debug tracing of tasks but we must
+           test for TRACE_STDERR because of the !eventlog_enabled case. */
+    } else
+#endif
+    {
+        EventTaskId         taskid = serialisableTaskId(task);
+        EventKernelThreadId tid    = kernelThreadId();
+        postTaskCreateEvent(taskid, cap->no, tid);
+    }
+}
+
+void traceTaskMigrate_ (Task       *task,
+                        Capability *cap,
+                        Capability *new_cap)
+{
+#ifdef DEBUG
+    if (RtsFlags.TraceFlags.tracing == TRACE_STDERR) {
+        /* We currently don't do debug tracing of tasks but we must
+           test for TRACE_STDERR because of the !eventlog_enabled case. */
+    } else
+#endif
+    {
+        EventTaskId taskid = serialisableTaskId(task);
+        postTaskMigrateEvent(taskid, cap->no, new_cap->no);
+    }
+}
+
+void traceTaskDelete_ (Task *task)
+{
+#ifdef DEBUG
+    if (RtsFlags.TraceFlags.tracing == TRACE_STDERR) {
+        /* We currently don't do debug tracing of tasks but we must
+           test for TRACE_STDERR because of the !eventlog_enabled case. */
+    } else
+#endif
+    {
+        EventTaskId taskid = serialisableTaskId(task);
+        postTaskDeleteEvent(taskid);
+    }
+}
+
 #ifdef DEBUG
 static void traceCap_stderr(Capability *cap, char *msg, va_list ap)
 {