x86: Add NMI duration tracepoints

This patch has been invaluable in my adventures finding
issues in the perf NMI handler.  I'm as big a fan of
printk() as anybody is, but using printk() in NMIs is
deadly when they're happening frequently.

Even hacking in trace_printk() ended up eating enough
CPU to throw off some of the measurements I was making.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: paulus@samba.org
Cc: acme@ghostprotocols.net
Cc: Dave Hansen <dave@sr71.net>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 37 insertions, 0 deletions

diff --git a/include/trace/events/nmi.h b/include/trace/events/nmi.h
new file mode 100644
index 000000000000..da3ee96b8d03
--- /dev/null
+++ b/include/trace/events/nmi.h
@@ -0,0 +1,37 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM nmi
+
+#if !defined(_TRACE_NMI_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_NMI_H
+
+#include <linux/ktime.h>
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(nmi_handler,
+
+        TP_PROTO(void *handler, s64 delta_ns, int handled),
+
+        TP_ARGS(handler, delta_ns, handled),
+
+        TP_STRUCT__entry(
+                __field(        void *,         handler )
+                __field(        s64,            delta_ns)
+                __field(        int,            handled )
+        ),
+
+        TP_fast_assign(
+                __entry->handler = handler;
+                __entry->delta_ns = delta_ns;
+                __entry->handled = handled;
+        ),
+
+        TP_printk("%ps() delta_ns: %lld handled: %d",
+                __entry->handler,
+                __entry->delta_ns,
+                __entry->handled)
+);
+
+#endif /* _TRACE_NMI_H */
+
+/* This part ust be outside protection */
+#include <trace/define_trace.h>