From: Jason Baron <jbaron@redhat.com>
Date: Tue, 23 Sep 2008 15:00:54 -0400
Subject: [misc] add tracepoints to activate/deactivate_task
Message-id: 20080923190054.GD3117@redhat.com
O-Subject: [RHEL5 patch] - add tracepoints to activate/deactivate_task()
Bugzilla: 461966

hi,

The following patch adds tracepoints to 'activate_task()' and
'deactivat_task()'. The patch satisfies a request from Alcatel Lucent.
The tracepoints are not invasive but do pose a potential performance
issue...however, we have not found any performance issues in regression
testing...resolves bz #461966.

thanks,

-Jason

diff --git a/include/trace/sched.h b/include/trace/sched.h
index 363b7f5..c22f968 100644
--- a/include/trace/sched.h
+++ b/include/trace/sched.h
@@ -6,6 +6,12 @@
 
 struct rq;
 
+DEFINE_TRACE(activate_task,
+	TPPROTO(struct task_struct *p, struct rq *rq),
+	TPARGS(p, rq));
+DEFINE_TRACE(deactivate_task,
+	TPPROTO(struct task_struct *p, struct rq *rq),
+	TPARGS(p, rq));
 DEFINE_TRACE(sched_wakeup,
 	TPPROTO(struct rq *rq, struct task_struct *p),
 	TPARGS(rq, p));
diff --git a/kernel/kernel-trace.c b/kernel/kernel-trace.c
index 720ef1a..9b211f8 100644
--- a/kernel/kernel-trace.c
+++ b/kernel/kernel-trace.c
@@ -20,6 +20,18 @@ static void probe_irq_exit(unsigned int id, irqreturn_t retval)
 	trace_mark(kernel_irq_exit, "irq_id %u retval %ld", id, (long)retval);
 }
 
+static void probe_activate_task(struct task_struct *p, struct rq *rq)
+{
+	trace_mark(kernel_activate_task, "pid %d state %ld cpu_id %u",
+		p->pid, p->state, task_cpu(p));
+}
+
+static void probe_deactivate_task(struct task_struct *p, struct rq *rq)
+{
+	trace_mark(kernel_deactivate_task, "pid %d state %ld cpu_id %u",
+		p->pid, p->state, task_cpu(p));
+}
+
 static void probe_sched_wakeup(struct rq *rq, struct task_struct *p)
 {
 	trace_mark(kernel_sched_wakeup, "pid %d state %ld cpu_id %u",
@@ -111,6 +123,12 @@ int __init kernel_trace_init(void)
 	WARN_ON(ret);
 	ret = register_trace_irq_exit(probe_irq_exit);
 	WARN_ON(ret);
+	ret = register_trace_activate_task(
+		probe_activate_task);
+	WARN_ON(ret);
+	ret = register_trace_deactivate_task(
+		probe_deactivate_task);
+	WARN_ON(ret);
 	ret = register_trace_sched_wakeup(
 		probe_sched_wakeup);
 	WARN_ON(ret);
@@ -171,6 +189,8 @@ void __exit kernel_trace_exit(void)
 		probe_sched_wakeup_new);
 	unregister_trace_sched_wakeup(
 		probe_sched_wakeup);
+	unregister_trace_deactivate_task(probe_deactivate_task);
+	unregister_trace_activate_task(probe_activate_task);
 	unregister_trace_irq_exit(probe_irq_exit);
 	unregister_trace_irq_entry(probe_irq_entry);
 }
diff --git a/kernel/sched.c b/kernel/sched.c
index 4037e50..acccea6 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -845,6 +845,7 @@ static void __activate_task(struct task_struct *p, struct rq *rq)
 {
 	struct prio_array *target = rq->active;
 
+	trace_activate_task(p, rq);
 	if (batch_task(p))
 		target = rq->expired;
 	enqueue_task(p, target);
@@ -987,6 +988,7 @@ static void deactivate_task(struct task_struct *p, struct rq *rq)
 {
 	dec_nr_running(p, rq);
 	dequeue_task(p, p->array);
+	trace_deactivate_task(p, rq);
 	p->array = NULL;
 }
 
@@ -1705,6 +1707,7 @@ void fastcall wake_up_new_task(struct task_struct *p, unsigned long clone_flags)
 			if (unlikely(!current->array))
 				__activate_task(p, rq);
 			else {
+				trace_activate_task(p, rq);
 				p->prio = current->prio;
 				p->normal_prio = current->normal_prio;
 				list_add_tail(&p->run_list, &current->run_list);