perfcounters: fix task clock counter

Impact: fix per task clock counter precision

Signed-off-by: Ingo Molnar <mingo@elte.hu>

kernel/sched.c

@@ -638,7 +638,7 @@ static inline int cpu_of(struct rq *rq)
 #define task_rq(p)		cpu_rq(task_cpu(p))
 #define cpu_curr(cpu)		(cpu_rq(cpu)->curr)
 
-static inline void update_rq_clock(struct rq *rq)
+inline void update_rq_clock(struct rq *rq)
 {
 	rq->clock = sched_clock_cpu(cpu_of(rq));
 }
@@ -969,6 +969,26 @@ static struct rq *task_rq_lock(struct task_struct *p, unsigned long *flags)
 	}
 }
 
+void curr_rq_lock_irq_save(unsigned long *flags)
+	__acquires(rq->lock)
+{
+	struct rq *rq;
+
+	local_irq_save(*flags);
+	rq = cpu_rq(smp_processor_id());
+	spin_lock(&rq->lock);
+}
+
+void curr_rq_unlock_irq_restore(unsigned long *flags)
+	__releases(rq->lock)
+{
+	struct rq *rq;
+
+	rq = cpu_rq(smp_processor_id());
+	spin_unlock(&rq->lock);
+	local_irq_restore(*flags);
+}
+
 void task_rq_unlock_wait(struct task_struct *p)
 {
 	struct rq *rq = task_rq(p);
@@ -2558,7 +2578,6 @@ prepare_task_switch(struct rq *rq, struct task_struct *prev,
 		    struct task_struct *next)
 {
 	fire_sched_out_preempt_notifiers(prev, next);
-	perf_counter_task_sched_out(prev, cpu_of(rq));
 	prepare_lock_switch(rq, next);
 	prepare_arch_switch(next);
 }
@@ -4089,6 +4108,29 @@ DEFINE_PER_CPU(struct kernel_stat, kstat);
 
 EXPORT_PER_CPU_SYMBOL(kstat);
 
+/*
+ * Return any ns on the sched_clock that have not yet been banked in
+ * @p in case that task is currently running.
+ */
+unsigned long long __task_delta_exec(struct task_struct *p, int update)
+{
+	s64 delta_exec;
+	struct rq *rq;
+
+	rq = task_rq(p);
+	WARN_ON_ONCE(!runqueue_is_locked());
+	WARN_ON_ONCE(!task_current(rq, p));
+
+	if (update)
+		update_rq_clock(rq);
+
+	delta_exec = rq->clock - p->se.exec_start;
+
+	WARN_ON_ONCE(delta_exec < 0);
+
+	return delta_exec;
+}
+
 /*
  * Return any ns on the sched_clock that have not yet been banked in
  * @p in case that task is currently running.
@@ -4316,13 +4358,13 @@ void scheduler_tick(void)
 	update_rq_clock(rq);
 	update_cpu_load(rq);
 	curr->sched_class->task_tick(rq, curr, 0);
+	perf_counter_task_tick(curr, cpu);
 	spin_unlock(&rq->lock);
 
 #ifdef CONFIG_SMP
 	rq->idle_at_tick = idle_cpu(cpu);
 	trigger_load_balance(rq, cpu);
 #endif
-	perf_counter_task_tick(curr, cpu);
 }
 
 #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
@@ -4512,6 +4554,7 @@ need_resched_nonpreemptible:
 
 	if (likely(prev != next)) {
 		sched_info_switch(prev, next);
+		perf_counter_task_sched_out(prev, cpu);
 
 		rq->nr_switches++;
 		rq->curr = next;