sched

draft: struct rq

##summary:

  1. struct rq is basic data structure.
  2. there is a realtime process(es) and normal process(es) are stored in
    different sub-runqueue *_rq of rq? 
    1
    2
    426         struct cfs_rq cfs;
    427         struct rt_rq rt;
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393 /*
394  * This is the main, per-CPU runqueue data structure.
395  *
396  * Locking rule: those places that want to lock multiple runqueues
397  * (such as the load balancing or the thread migration code), lock
398  * acquire operations must be ordered by ascending &runqueue.
399  */
400 struct rq {
401         /* runqueue lock: */
402         raw_spinlock_t lock;
403 
404         /*
405          * nr_running and cpu_load should be in the same cacheline because
406          * remote CPUs use both these fields when doing load calculation.
407          */
408         unsigned int nr_running;
409         #define CPU_LOAD_IDX_MAX 5
410         unsigned long cpu_load[CPU_LOAD_IDX_MAX];
411         unsigned long last_load_update_tick;
412 #ifdef CONFIG_NO_HZ_COMMON
413         u64 nohz_stamp;
414         unsigned long nohz_flags;
415 #endif
416 #ifdef CONFIG_NO_HZ_FULL
417         unsigned long last_sched_tick;
418 #endif
419         int skip_clock_update;
420 
421         /* capture load from *all* tasks on this cpu: */
422         struct load_weight load;
423         unsigned long nr_load_updates;
424         u64 nr_switches;
425 
426         struct cfs_rq cfs;
427         struct rt_rq rt;
428 
429 #ifdef CONFIG_FAIR_GROUP_SCHED
430         /* list of leaf cfs_rq on this cpu: */
431         struct list_head leaf_cfs_rq_list;
432 #ifdef CONFIG_SMP
433         unsigned long h_load_throttle;
434 #endif /* CONFIG_SMP */
435 #endif /* CONFIG_FAIR_GROUP_SCHED */
436 
437 #ifdef CONFIG_RT_GROUP_SCHED
438         struct list_head leaf_rt_rq_list;
439 #endif
440 
441         /*
442          * This is part of a global counter where only the total sum
443          * over all CPUs matters. A task can increase this counter on
444          * one CPU and if it got migrated afterwards it may decrease
445          * it on another CPU. Always updated under the runqueue lock:
446          */
447         unsigned long nr_uninterruptible;
448 
449         struct task_struct *curr, *idle, *stop;
450         unsigned long next_balance;
451         struct mm_struct *prev_mm;
452 
453         u64 clock;
454         u64 clock_task;
455 
456         atomic_t nr_iowait;
457 
458 #ifdef CONFIG_SMP
459         struct root_domain *rd;
460         struct sched_domain *sd;
461 
462         unsigned long cpu_power;
463 
464         unsigned char idle_balance;
465         /* For active balancing */
466         int post_schedule;
467         int active_balance;
468         int push_cpu;
469         struct cpu_stop_work active_balance_work;
470         /* cpu of this runqueue: */
471         int cpu;
472         int online;
473 
474         struct list_head cfs_tasks;
475 
476         u64 rt_avg;
477         u64 age_stamp;
478         u64 idle_stamp;
479         u64 avg_idle;
480 #endif
481 
482 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
483         u64 prev_irq_time;
484 #endif
485 #ifdef CONFIG_PARAVIRT
486         u64 prev_steal_time;
487 #endif
488 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
489         u64 prev_steal_time_rq;
490 #endif
491 
492         /* calc_load related fields */
493         unsigned long calc_load_update;
494         long calc_load_active;
495 
496 #ifdef CONFIG_SCHED_HRTICK
497 #ifdef CONFIG_SMP
498         int hrtick_csd_pending;
499         struct call_single_data hrtick_csd;
500 #endif
501         struct hrtimer hrtick_timer;
502 #endif
503 
504 #ifdef CONFIG_SCHEDSTATS
505         /* latency stats */
506         struct sched_info rq_sched_info;
507         unsigned long long rq_cpu_time;
508         /* could above be rq->cfs_rq.exec_clock + rq->rt_rq.rt_runtime ? */
509 
510         /* sys_sched_yield() stats */
511         unsigned int yld_count;
512 
513         /* schedule() stats */
514         unsigned int sched_count;
515         unsigned int sched_goidle;
516 
517         /* try_to_wake_up() stats */
518         unsigned int ttwu_count;
519         unsigned int ttwu_local;
520 #endif
521 
522 #ifdef CONFIG_SMP
523         struct llist_head wake_list;
524 #endif
525 
526         struct sched_avg avg;
527 };