sched: add latency tracer callbacks to the scheduler

add 3 lightweight callbacks to the tracer backend.

zero impact if tracing is turned off.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 5395a6176f4be13911a57d7174de0274947edb94..717cab8a0c835867137bf33f6b6e5090d562fc2f 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2117,6 +2117,32 @@ static inline void arch_pick_mmap_layout(struct mm_struct *mm)
 }
 #endif
 
+#ifdef CONFIG_CONTEXT_SWITCH_TRACER
+extern void
+ftrace_ctx_switch(struct task_struct *prev, struct task_struct *next);
+#else
+static inline void
+ftrace_ctx_switch(struct task_struct *prev, struct task_struct *next)
+{
+}
+#endif
+
+#ifdef CONFIG_SCHED_TRACER
+extern void
+ftrace_wake_up_task(struct task_struct *wakee, struct task_struct *curr);
+extern void
+ftrace_wake_up_new_task(struct task_struct *wakee, struct task_struct *curr);
+#else
+static inline void
+ftrace_wake_up_task(struct task_struct *wakee, struct task_struct *curr)
+{
+}
+static inline void
+ftrace_wake_up_new_task(struct task_struct *wakee, struct task_struct *curr)
+{
+}
+#endif
+
 extern long sched_setaffinity(pid_t pid, const cpumask_t *new_mask);
 extern long sched_getaffinity(pid_t pid, cpumask_t *mask);
 

diff --git a/kernel/sched.c b/kernel/sched.c
index cfa222a91539e193a54d20d422fa92b43a19334b..463dcdb36ef82007b3f21343da219aab575e1f09 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2467,6 +2467,7 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync)
 
 out_activate:
 #endif /* CONFIG_SMP */
+       ftrace_wake_up_task(p, rq->curr);
        schedstat_inc(p, se.nr_wakeups);
        if (sync)
                schedstat_inc(p, se.nr_wakeups_sync);
@@ -2611,6 +2612,7 @@ void wake_up_new_task(struct task_struct *p, unsigned long clone_flags)
                p->sched_class->task_new(rq, p);
                inc_nr_running(rq);
        }
+       ftrace_wake_up_new_task(p, rq->curr);
        check_preempt_curr(rq, p);
 #ifdef CONFIG_SMP
        if (p->sched_class->task_wake_up)
@@ -2783,6 +2785,7 @@ context_switch(struct rq *rq, struct task_struct *prev,
        struct mm_struct *mm, *oldmm;
 
        prepare_task_switch(rq, prev, next);
+       ftrace_ctx_switch(prev, next);
        mm = next->mm;
        oldmm = prev->active_mm;
        /*