Re: [PATCH v3 2/7] sched: make struct sched_statistics independent of fair sched class

Peter Zijlstra
2021-08-31T10:20:13Z

On Tue, Aug 24, 2021 at 11:29:41AM +0000, Yafang Shao wrote:

> +#ifdef CONFIG_FAIR_GROUP_SCHED
> +static inline void
> +__schedstats_from_sched_entity(struct sched_entity *se,
> + struct sched_statistics **stats)
> +{
> + struct task_group *tg;
> + struct task_struct *p;
> + struct cfs_rq *cfs;
> + int cpu;
> +
> + if (entity_is_task(se)) {
> + p = task_of(se);
> + *stats = &p->stats;
> + } else {
> + cfs = group_cfs_rq(se);
> + tg = cfs->tg;
> + cpu = cpu_of(rq_of(cfs));
> + *stats = tg->stats[cpu];
> + }
> +}
> +
> +#else
> +
> +static inline void
> +__schedstats_from_sched_entity(struct sched_entity *se,
> + struct sched_statistics **stats)
> +{
> + struct task_struct *p;
> +
> + p = task_of(se);
> + *stats = &p->stats;
> +}
> +
> +#endif
> +
> /*
> * Update the current task's runtime statistics.
> */
> @@ -826,6 +861,7 @@ static void update_curr(struct cfs_rq *cfs_rq)
> {
> struct sched_entity *curr = cfs_rq->curr;
> u64 now = rq_clock_task(rq_of(cfs_rq));
> + struct sched_statistics *stats = NULL;
> u64 delta_exec;
>
> if (unlikely(!curr))
> @@ -837,8 +873,11 @@ static void update_curr(struct cfs_rq *cfs_rq)
>
> curr->exec_start = now;
>
> - schedstat_set(curr->statistics.exec_max,
> - max(delta_exec, curr->statistics.exec_max));
> + if (schedstat_enabled()) {
> + __schedstats_from_sched_entity(curr, &stats);
> + __schedstat_set(stats->exec_max,
> + max(delta_exec, stats->exec_max));
> + }
>
> curr->sum_exec_runtime += delta_exec;
> schedstat_add(cfs_rq->exec_clock, delta_exec);

That's just really odd style; what's wrong with something like:

static inline struct sched_statistics *
__schedstats_from_se(struct sched_entity *se)
{
...
}

if (schedstats_enabled()) {
struct sched_statistics *stats = __schedstats_from_se(curr);
__schedstat_set(stats->exec_max, max(stats->exec_max, delta_exec));
}