Commit-ID: 9ee1983c9aa18f12388ef660d0c76a23dc112959
Gitweb: http://git.kernel.org/tip/9ee1983c9aa18f12388ef660d0c76a23dc112959
Author: Jason Baron <jbaron@xxxxxxxxxx>
AuthorDate: Thu, 30 Apr 2009 13:29:47 -0400
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Fri, 1 May 2009 14:03:36 +0200
tracing: add irq tracepoint documentation
Document irqs for the newly created docbook.
[ Impact: add documentation ]
Signed-off-by: Jason Baron <jbaron@xxxxxxxxxx>
Acked-by: Randy Dunlap <randy.dunlap@xxxxxxxxxx>
Cc: akpm@xxxxxxxxxxxxxxxxxxxx
Cc: rostedt@xxxxxxxxxxx
Cc: fweisbec@xxxxxxxxx
Cc: mathieu.desnoyers@xxxxxxxxxx
Cc: wcohen@xxxxxxxxxx
LKML-Reference: <73ff42be3420157667ec548e9b0e409c3cfad05f.1241107197.git.jbaron@xxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
Documentation/DocBook/tracepoint.tmpl | 5 +++
include/trace/events/irq.h | 46 ++++++++++++++++++++++++++++++---
2 files changed, 47 insertions(+), 4 deletions(-)
diff --git a/Documentation/DocBook/tracepoint.tmpl b/Documentation/DocBook/tracepoint.tmpl
index 70891bc..b0756d0 100644
--- a/Documentation/DocBook/tracepoint.tmpl
+++ b/Documentation/DocBook/tracepoint.tmpl
@@ -81,4 +81,9 @@
</para>
</chapter>
+ <chapter id="irq">
+ <title>IRQ</title>
+!Iinclude/trace/events/irq.h
+ </chapter>
+
</book>
diff --git a/include/trace/events/irq.h b/include/trace/events/irq.h
index 7686864..32a9f7e 100644
--- a/include/trace/events/irq.h
+++ b/include/trace/events/irq.h
@@ -7,8 +7,16 @@
#undef TRACE_SYSTEM
#define TRACE_SYSTEM irq
-/*
- * Tracepoint for entry of interrupt handler:
+/**
+ * irq_handler_entry - called immediately before the irq action handler
+ * @irq: irq number
+ * @action: pointer to struct irqaction
+ *
+ * The struct irqaction pointed to by @action contains various
+ * information about the handler, including the device name,
+ * @action->name, and the device id, @action->dev_id. When used in
+ * conjunction with the irq_handler_exit tracepoint, we can figure
+ * out irq handler latencies.
*/
TRACE_EVENT(irq_handler_entry,
@@ -29,8 +37,16 @@ TRACE_EVENT(irq_handler_entry,
TP_printk("irq=%d handler=%s", __entry->irq, __get_str(name))
);
-/*
- * Tracepoint for return of an interrupt handler:
+/**
+ * irq_handler_exit - called immediately after the irq action handler returns
+ * @irq: irq number
+ * @action: pointer to struct irqaction
+ * @ret: return value
+ *
+ * If the @ret value is set to IRQ_HANDLED, then we know that the corresponding
+ * @action->handler scuccessully handled this irq. Otherwise, the irq might be
+ * a shared irq line, or the irq was not handled successfully. Can be used in
+ * conjunction with the irq_handler_entry to understand irq handler latencies.
*/
TRACE_EVENT(irq_handler_exit,
@@ -52,6 +68,17 @@ TRACE_EVENT(irq_handler_exit,
__entry->irq, __entry->ret ? "handled" : "unhandled")
);
+/**
+ * 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
+ *
+ * The @h parameter, contains a pointer to the struct softirq_action
+ * which has a pointer to the action handler that is called. By subtracting
+ * the @vec pointer from the @h pointer, we can determine the softirq
+ * number. Also, when used in combination with the softirq_exit tracepoint
+ * we can determine the softirq latency.
+ */
TRACE_EVENT(softirq_entry,
TP_PROTO(struct softirq_action *h, struct softirq_action *vec),
@@ -71,6 +98,17 @@ TRACE_EVENT(softirq_entry,
TP_printk("softirq=%d action=%s", __entry->vec, __get_str(name))
);
+/**
+ * softirq_exit - called immediately after the softirq handler returns
+ * @h: pointer to struct softirq_action
+ * @vec: pointer to first struct softirq_action in softirq_vec array
+ *
+ * The @h parameter contains a pointer to the struct softirq_action
+ * that has handled the softirq. By subtracting the @vec pointer from
+ * the @h pointer, we can determine the softirq number. Also, when used in
+ * combination with the softirq_entry tracepoint we can determine the softirq
+ * latency.
+ */
TRACE_EVENT(softirq_exit,
TP_PROTO(struct softirq_action *h, struct softirq_action *vec),
--
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