Re: [PATCH 4/5] sched/debug: remove several CONFIG_SCHEDSTATS guards

[Peter Zijlstra]

On Fri, Jun 17, 2016 at 12:43:26PM -0500, Josh Poimboeuf wrote:
> index 017a4f5..0aee5dd 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -1626,10 +1626,15 @@ static inline int __set_cpus_allowed_ptr(struct 
> task_struct *p,
>  static void
>  ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
>  {
> -#ifdef CONFIG_SCHEDSTATS
> -     struct rq *rq = this_rq();
> +     struct rq *rq;
> +
> +     if (!schedstat_enabled())
> +             return;
> +
> +     rq = this_rq();
>  
>  #ifdef CONFIG_SMP
> +{
>       int this_cpu = smp_processor_id();
>  
>       if (cpu == this_cpu) {
> @@ -1651,7 +1656,7 @@ ttwu_stat(struct task_struct *p, int cpu, int 
> wake_flags)
>  
>       if (wake_flags & WF_MIGRATED)
>               schedstat_inc(p->se.statistics.nr_wakeups_migrate);
> -
> +}
>  #endif /* CONFIG_SMP */
>  
>       schedstat_inc(rq->ttwu_count);

I did:

--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1636,10 +1636,7 @@ ttwu_stat(struct task_struct *p, int cpu
        rq = this_rq();
 
 #ifdef CONFIG_SMP
-{
-       int this_cpu = smp_processor_id();
-
-       if (cpu == this_cpu) {
+       if (cpu == rq->cpu) {
                schedstat_inc(rq->ttwu_local);
                schedstat_inc(p->se.statistics.nr_wakeups_local);
        } else {
@@ -1647,7 +1644,7 @@ ttwu_stat(struct task_struct *p, int cpu
 
                schedstat_inc(p->se.statistics.nr_wakeups_remote);
                rcu_read_lock();
-               for_each_domain(this_cpu, sd) {
+               for_each_domain(rq->cpu, sd) {
                        if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
                                schedstat_inc(sd->ttwu_wake_remote);
                                break;
@@ -1658,7 +1655,6 @@ ttwu_stat(struct task_struct *p, int cpu
 
        if (wake_flags & WF_MIGRATED)
                schedstat_inc(p->se.statistics.nr_wakeups_migrate);
-}
 #endif /* CONFIG_SMP */
 
        schedstat_inc(rq->ttwu_count);