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

Jason Baron
2009-03-16T19:40:00Z

On Mon, Mar 16, 2009 at 03:17:09PM -0400, Steven Rostedt wrote:
> memcpy isn't fast ;-)
>
> What you want is this:
>
> TP_STRUCT__entry(
> __field( int, vec )
> ),
>
> TP_fast_assign(
> __entry->vec = h - vec;

definitely simplifies things! ok, re-spun patch again.

use TRACE_EVENT to record the softirq vector number in the trace and then use
the new softirq_to_name array to output the softirq vector name.

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

---

include/trace/irq_event_types.h | 34 ++++++++++++++++++++++++++++++++++
kernel/softirq.c | 7 ++++++-
2 files changed, 40 insertions(+), 1 deletions(-)

diff --git a/include/trace/irq_event_types.h b/include/trace/irq_event_types.h
index 214bb92..acb8217 100644
--- a/include/trace/irq_event_types.h
+++ b/include/trace/irq_event_types.h
@@ -40,4 +40,38 @@ TRACE_EVENT(irq_handler_exit,
__entry->irq, __entry->ret ? "handled" : "unhandled")
);

+TRACE_EVENT(softirq_action_entry,
+
+ TP_PROTO(struct softirq_action *h, struct softirq_action *vec),
+
+ TP_ARGS(h, vec),
+
+ TP_STRUCT__entry(
+ __field( int, vec )
+ ),
+
+ TP_fast_assign(
+ __entry->vec = h - vec;
+ ),
+
+ TP_printk("softirq entry: %s", softirq_to_name[__entry->vec])
+);
+
+TRACE_EVENT(softirq_action_exit,
+
+ TP_PROTO(struct softirq_action *h, struct softirq_action *vec),
+
+ TP_ARGS(h, vec),
+
+ TP_STRUCT__entry(
+ __field( int, vec )
+ ),
+
+ TP_fast_assign(
+ __entry->vec = h - vec;
+ ),
+
+ TP_printk("softirq exit: %s", softirq_to_name[__entry->vec])
+);
+
#undef TRACE_SYSTEM
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 8f3ae57..5e96c77 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>
/*
@@ -185,6 +186,9 @@ EXPORT_SYMBOL(local_bh_enable_ip);
*/
#define MAX_SOFTIRQ_RESTART 10

+DEFINE_TRACE(softirq_action_entry);
+DEFINE_TRACE(softirq_action_exit);
+
asmlinkage void __do_softirq(void)
{
struct softirq_action *h;
@@ -211,8 +215,9 @@ restart:
if (pending & 1) {
int prev_count = preempt_count();

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