Re: [PATCH] sched: remove rq's runnable load average

[Vincent Guittot]

Hi Yuyang,

I have started to use it in this patchset https://lkml.org/lkml/2014/5/23/458

Regards,
Vincent

On 5 June 2014 00:51, Yuyang Du <yuyang.du@xxxxxxxxx> wrote:
> Per rq runnable average has not been made use of anywhere since it was merged by:
>
> commit 18bf2805d9b30cb823d4919b42cd230f59c7ce1f
> Author: Ben Segall <bsegall@xxxxxxxxxx>
> Date:   Thu Oct 4 12:51:20 2012 +0200
>
>     sched: Maintain per-rq runnable averages
>
>     Since runqueues do not have a corresponding sched_entity we instead embed a
>     sched_avg structure directly.
>
>     Signed-off-by: Ben Segall <bsegall@xxxxxxxxxx>
>     Reviewed-by: Paul Turner <pjt@xxxxxxxxxx>
>     Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
>     Link: http://lkml.kernel.org/r/20120823141506.442637130@xxxxxxxxxx
>     Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
>
> So removing it does not hurt anything but can benefit PnP as the average trakcing
> is in scheduler critical path.
>
> Signed-off-by: Yuyang Du <yuyang.du@xxxxxxxxx>
> ---
>  kernel/sched/debug.c |  8 --------
>  kernel/sched/fair.c  | 24 ++++--------------------
>  kernel/sched/sched.h |  2 --
>  3 files changed, 4 insertions(+), 30 deletions(-)
>
> diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
> index 695f977..4b864c7 100644
> --- a/kernel/sched/debug.c
> +++ b/kernel/sched/debug.c
> @@ -68,14 +68,6 @@ static void print_cfs_group_stats(struct seq_file *m, int cpu, struct task_group
>  #define PN(F) \
>         SEQ_printf(m, "  .%-30s: %lld.%06ld\n", #F, SPLIT_NS((long long)F))
>
> -       if (!se) {
> -               struct sched_avg *avg = &cpu_rq(cpu)->avg;
> -               P(avg->runnable_avg_sum);
> -               P(avg->runnable_avg_period);
> -               return;
> -       }
> -
> -
>         PN(se->exec_start);
>         PN(se->vruntime);
>         PN(se->sum_exec_runtime);
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 0fdb96d..18ee21d 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -2378,18 +2378,12 @@ static inline void __update_group_entity_contrib(struct sched_entity *se)
>         }
>  }
>
> -static inline void update_rq_runnable_avg(struct rq *rq, int runnable)
> -{
> -       __update_entity_runnable_avg(rq_clock_task(rq), &rq->avg, runnable);
> -       __update_tg_runnable_avg(&rq->avg, &rq->cfs);
> -}
>  #else /* CONFIG_FAIR_GROUP_SCHED */
>  static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq,
>                                                  int force_update) {}
>  static inline void __update_tg_runnable_avg(struct sched_avg *sa,
>                                                   struct cfs_rq *cfs_rq) {}
>  static inline void __update_group_entity_contrib(struct sched_entity *se) {}
> -static inline void update_rq_runnable_avg(struct rq *rq, int runnable) {}
>  #endif /* CONFIG_FAIR_GROUP_SCHED */
>
>  static inline void __update_task_entity_contrib(struct sched_entity *se)
> @@ -2562,7 +2556,6 @@ static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq,
>   */
>  void idle_enter_fair(struct rq *this_rq)
>  {
> -       update_rq_runnable_avg(this_rq, 1);
>  }
>
>  /*
> @@ -2572,7 +2565,6 @@ void idle_enter_fair(struct rq *this_rq)
>   */
>  void idle_exit_fair(struct rq *this_rq)
>  {
> -       update_rq_runnable_avg(this_rq, 0);
>  }
>
>  static int idle_balance(struct rq *this_rq);
> @@ -2581,7 +2573,6 @@ static int idle_balance(struct rq *this_rq);
>
>  static inline void update_entity_load_avg(struct sched_entity *se,
>                                           int update_cfs_rq) {}
> -static inline void update_rq_runnable_avg(struct rq *rq, int runnable) {}
>  static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq,
>                                            struct sched_entity *se,
>                                            int wakeup) {}
> @@ -3882,10 +3873,9 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
>                 update_entity_load_avg(se, 1);
>         }
>
> -       if (!se) {
> -               update_rq_runnable_avg(rq, rq->nr_running);
> +       if (!se)
>                 inc_nr_running(rq);
> -       }
> +
>         hrtick_update(rq);
>  }
>
> @@ -3943,10 +3933,9 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
>                 update_entity_load_avg(se, 1);
>         }
>
> -       if (!se) {
> +       if (!se)
>                 dec_nr_running(rq);
> -               update_rq_runnable_avg(rq, 1);
> -       }
> +
>         hrtick_update(rq);
>  }
>
> @@ -5364,9 +5353,6 @@ static void __update_blocked_averages_cpu(struct task_group *tg, int cpu)
>                  */
>                 if (!se->avg.runnable_avg_sum && !cfs_rq->nr_running)
>                         list_del_leaf_cfs_rq(cfs_rq);
> -       } else {
> -               struct rq *rq = rq_of(cfs_rq);
> -               update_rq_runnable_avg(rq, rq->nr_running);
>         }
>  }
>
> @@ -7243,8 +7229,6 @@ static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued)
>
>         if (numabalancing_enabled)
>                 task_tick_numa(rq, curr);
> -
> -       update_rq_runnable_avg(rq, 1);
>  }
>
>  /*
> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> index 456e492..5a66776 100644
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -552,8 +552,6 @@ struct rq {
>  #ifdef CONFIG_FAIR_GROUP_SCHED
>         /* list of leaf cfs_rq on this cpu: */
>         struct list_head leaf_cfs_rq_list;
> -
> -       struct sched_avg avg;
>  #endif /* CONFIG_FAIR_GROUP_SCHED */
>
>         /*
> --
> 1.9.1
>
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