[Patch 2/2] tracepoints for softirq entry/exit - tracepoints

Jason Baron
2009-03-12T18:38:18Z

introduce softirq entry/exit tracepoints. These are useful for
augmenting existing tracers, and to figure out softirq frequencies and
timings.

Signed-off-by: Jason Baron <jbaron@redhat.com>

---

include/trace/irq_event_types.h | 12 ++++++++++++
kernel/softirq.c | 7 ++++++-
2 files changed, 18 insertions(+), 1 deletions(-)

diff --git a/include/trace/irq_event_types.h b/include/trace/irq_event_types.h
index 214bb92..38b4bdd 100644
--- a/include/trace/irq_event_types.h
+++ b/include/trace/irq_event_types.h
@@ -40,4 +40,16 @@ TRACE_EVENT(irq_handler_exit,
__entry->irq, __entry->ret ? "handled" : "unhandled")
);

+TRACE_FORMAT(irq_softirq_entry,
+ TP_PROTO(struct softirq_action *h, struct softirq_action *vec),
+ TP_ARGS(h, vec),
+ TP_FMT("softirq=%d action=%s", h - vec, softirq_to_name[h-vec])
+ );
+
+TRACE_FORMAT(irq_softirq_exit,
+ TP_PROTO(struct softirq_action *h, struct softirq_action *vec),
+ TP_ARGS(h, vec),
+ TP_FMT("softirq=%d action=%s", h - vec, softirq_to_name[h-vec])
+ );
+
#undef TRACE_SYSTEM
diff --git a/kernel/softirq.c b/kernel/softirq.c
index ba1511f..c378d53 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -24,6 +24,7 @@
#include <linux/ftrace.h>
#include <linux/smp.h>
#include <linux/tick.h>
+#include <trace/irq.h>

#include <asm/irq.h>
/*
@@ -186,6 +187,9 @@ EXPORT_SYMBOL(local_bh_enable_ip);
*/
#define MAX_SOFTIRQ_RESTART 10

+DEFINE_TRACE(irq_softirq_entry);
+DEFINE_TRACE(irq_softirq_exit);
+
asmlinkage void __do_softirq(void)
{
struct softirq_action *h;
@@ -212,8 +216,9 @@ restart:
if (pending & 1) {
int prev_count = preempt_count();

+ trace_irq_softirq_entry(h, softirq_vec);
h->action(h);
-
+ trace_irq_softirq_exit(h, softirq_vec);
if (unlikely(prev_count != preempt_count())) {
printk(KERN_ERR "huh, entered softirq %td %s %p"
"with preempt_count %08x,"