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

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Date:	Thu, 05 Nov 2009 15:54:55 +0800
From:	Lai Jiangshan <laijs@...fujitsu.com>
To:	Ingo Molnar <mingo@...e.hu>, Steven Rostedt <rostedt@...dmis.org>,
	fweisbec@...il.com
CC:	Xiao Guangrong <xiaoguangrong@...fujitsu.com>,
	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
	linux-kernel@...r.kernel.org, zhaolei@...fujitsu.com,
	Xiao Guangrong <xiaoguangrong@...fujitsu.com>,
	Li Zefan <lizf@...fujitsu.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jason Baron <jbaron@...hat.com>
Subject: [PATCH] softirq,tracing: enable to trace softirq raise latency


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@...fujitsu.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 dcfcd44..799af09 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)				\
@@ -83,6 +85,32 @@ TRACE_EVENT(irq_handler_exit,
 );
 
 /**
+ * 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))
+);
+
+/**
  * softirq_entry - called immediately before the softirq handler
  * @h: pointer to struct softirq_action
  * @vec: pointer to first struct softirq_action in softirq_vec array
@@ -100,11 +128,11 @@ TRACE_EVENT(softirq_entry,
 	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,
@@ -129,11 +157,11 @@ TRACE_EVENT(softirq_exit,
 	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,

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