Merge pull request #201 from sched-ext/htejun/dump

Improve debug dump

Documentation/scheduler/sched-ext.rst

@@ -18,6 +18,13 @@ programs - the BPF scheduler.
   a runnable task stalls, or on invoking the SysRq key sequence
   :kbd:`SysRq-S`.
 
+* When the BPF scheduler triggers an error, debug information is dumped to
+  aid debugging. The debug dump is passed to and printed out by the
+  scheduler binary. The debug dump can also be accessed through the
+  `sched_ext_dump` tracepoint. The SysRq key sequence :kbd:`SysRq-D`
+  triggers a debug dump. This doesn't terminate the BPF scheduler and can
+  only be read through the tracepoint.
+
 Switching to and from sched_ext
 ===============================
 

include/trace/events/sched_ext.h

@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM sched_ext
+
+#if !defined(_TRACE_SCHED_EXT_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_SCHED_EXT_H
+
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(sched_ext_dump,
+
+	TP_PROTO(const char *line),
+
+	TP_ARGS(line),
+
+	TP_STRUCT__entry(
+		__string(line, line)
+	),
+
+	TP_fast_assign(
+		__assign_str(line, line);
+	),
+
+	TP_printk("%s",
+		__get_str(line)
+	)
+);
+
+#endif /* _TRACE_SCHED_EXT_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>