[PATCH] softirq,tracing: enable to trace softirq raise lat..

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


From: Lai Jiangshan <laijs.DeleteThis@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.DeleteThis@cn.fujitsu.com>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers.DeleteThis@polymtl.ca>
Acked-by: Frederic Weisbecker <fweisbec.DeleteThis@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,
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* Lai Jiangshan <laijs DeleteThis @cn.fujitsu.com> wrote:

> Rebase it for the newly codes
> Collect Acks(Acked-by Mathieu Desnoyers and Frederic Weisbecker)
>
>
> From: Lai Jiangshan <laijs DeleteThis @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 DeleteThis @cn.fujitsu.com>
> Acked-by: Mathieu Desnoyers <mathieu.desnoyers DeleteThis @polymtl.ca>
> Acked-by: Frederic Weisbecker <fweisbec DeleteThis @gmail.com>

ok, it would be nice to expose this functionality via some sort of 'perf
trace --irqlatency' (or perhaps a separate 'perf irq record' 'perf irq
trace' tool) so that users/developers can make use of this new event and
that we can check that it works and latencies are correct, etc.

Ingo
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