[PATCH] softirq,tracing: enable to trace softirq raise latency

From: Lai Jiangshan <laijs@cn.fujitsu.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>,
	Steven Rostedt <rostedt@goodmis.org>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: [PATCH] softirq,tracing: enable to trace softirq raise latency
Date: Tue, 08 Dec 2009 16:32:27 +0800	[thread overview]
Message-ID: <4B1E0F1B.7020305@cn.fujitsu.com> (raw)

Rebase it for the newly codes
Collect Acks(Acked-by Mathieu Desnoyers and Frederic Weisbecker)


From: Lai Jiangshan <laijs@cn.fujitsu.com>

Add a tracepoint for tracing when softirq action is raised.

It and the existed tracepoints complete softirq's tracepoints:
softirq_raise, softirq_entry and softirq_exit.

And when this tracepoint is used in combination with
the softirq_entry tracepoint we can determine
the softirq raise latency.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
---

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 75f3f00..b368d5d 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -18,6 +18,7 @@
 #include <asm/atomic.h>
 #include <asm/ptrace.h>
 #include <asm/system.h>
+#include <trace/events/irq.h>
 
 /*
  * These correspond to the IORESOURCE_IRQ_* defines in
@@ -372,7 +373,13 @@ asmlinkage void do_softirq(void);
 asmlinkage void __do_softirq(void);
 extern void open_softirq(int nr, void (*action)(struct softirq_action *));
 extern void softirq_init(void);
-#define __raise_softirq_irqoff(nr) do { or_softirq_pending(1UL << (nr)); } while (0)
+
+static inline void __raise_softirq_irqoff(unsigned int nr)
+{
+	trace_softirq_raise(nr);
+	or_softirq_pending(1UL << nr);
+}
+
 extern void raise_softirq_irqoff(unsigned int nr);
 extern void raise_softirq(unsigned int nr);
 extern void wakeup_softirqd(void);
diff --git a/include/trace/events/irq.h b/include/trace/events/irq.h
index 0e4cfb6..7a21fe2 100644
--- a/include/trace/events/irq.h
+++ b/include/trace/events/irq.h
@@ -5,7 +5,9 @@
 #define _TRACE_IRQ_H
 
 #include <linux/tracepoint.h>
-#include <linux/interrupt.h>
+
+struct irqaction;
+struct softirq_action;
 
 #define softirq_name(sirq) { sirq##_SOFTIRQ, #sirq }
 #define show_softirq_name(val)				\
@@ -82,6 +84,32 @@ TRACE_EVENT(irq_handler_exit,
 		  __entry->irq, __entry->ret ? "handled" : "unhandled")
 );
 
+/**
+ * softirq_raise - called immediately when a softirq is raised
+ * @nr: softirq vector number
+ *
+ * Tracepoint for tracing when softirq action is raised.
+ * Also, when used in combination with the softirq_entry tracepoint
+ * we can determine the softirq raise latency.
+ */
+TRACE_EVENT(softirq_raise,
+
+	TP_PROTO(unsigned int nr),
+
+	TP_ARGS(nr),
+
+	TP_STRUCT__entry(
+		__field(	unsigned int,	vec		)
+	),
+
+	TP_fast_assign(
+		__entry->vec	= nr;
+	),
+
+	TP_printk("vec=%d [action=%s]", __entry->vec,
+		  show_softirq_name(__entry->vec))
+);
+
 DECLARE_EVENT_CLASS(softirq,
 
 	TP_PROTO(struct softirq_action *h, struct softirq_action *vec),
@@ -89,11 +117,11 @@ DECLARE_EVENT_CLASS(softirq,
 	TP_ARGS(h, vec),
 
 	TP_STRUCT__entry(
-		__field(	int,	vec			)
+		__field(	unsigned int,	vec		)
 	),
 
 	TP_fast_assign(
-		__entry->vec = (int)(h - vec);
+		__entry->vec = (unsigned int)(h - vec);
 	),
 
 	TP_printk("vec=%d [action=%s]", __entry->vec,
