kernel/sched/stats.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2
   3 #ifdef CONFIG_SCHEDSTATS
   4
   5 /*
   6  * Expects runqueue lock to be held for atomicity of update
   7  */
   8 static inline void
   9 rq_sched_info_arrive(struct rq *rq, unsigned long long delta)
  10 {
  11         if (rq) {
  12                 rq->rq_sched_info.run_delay += delta;
  13                 rq->rq_sched_info.pcount++;
  14         }
  15 }
  16
  17 /*
  18  * Expects runqueue lock to be held for atomicity of update
  19  */
  20 static inline void
  21 rq_sched_info_depart(struct rq *rq, unsigned long long delta)
  22 {
  23         if (rq)
  24                 rq->rq_cpu_time += delta;
  25 }
  26
  27 static inline void
  28 rq_sched_info_dequeued(struct rq *rq, unsigned long long delta)
  29 {
  30         if (rq)
  31                 rq->rq_sched_info.run_delay += delta;
  32 }
  33 #define schedstat_enabled()             static_branch_unlikely(&sched_schedstats)
  34 #define __schedstat_inc(var)            do { var++; } while (0)
  35 #define schedstat_inc(var)              do { if (schedstat_enabled()) { var++; } } while (0)
  36 #define __schedstat_add(var, amt)       do { var += (amt); } while (0)
  37 #define schedstat_add(var, amt)         do { if (schedstat_enabled()) { var += (amt); } } while (0)
  38 #define __schedstat_set(var, val)               do { var = (val); } while (0)
  39 #define schedstat_set(var, val)         do { if (schedstat_enabled()) { var = (val); } } while (0)
  40 #define schedstat_val(var)              (var)
  41 #define schedstat_val_or_zero(var)      ((schedstat_enabled()) ? (var) : 0)
  42
  43 #else /* !CONFIG_SCHEDSTATS */
  44 static inline void
  45 rq_sched_info_arrive(struct rq *rq, unsigned long long delta)
  46 {}
  47 static inline void
  48 rq_sched_info_dequeued(struct rq *rq, unsigned long long delta)
  49 {}
  50 static inline void
  51 rq_sched_info_depart(struct rq *rq, unsigned long long delta)
  52 {}
  53 #define schedstat_enabled()             0
  54 #define __schedstat_inc(var)            do { } while (0)
  55 #define schedstat_inc(var)              do { } while (0)
  56 #define __schedstat_add(var, amt)       do { } while (0)
  57 #define schedstat_add(var, amt)         do { } while (0)
  58 #define __schedstat_set(var, val)       do { } while (0)
  59 #define schedstat_set(var, val)         do { } while (0)
  60 #define schedstat_val(var)              0
  61 #define schedstat_val_or_zero(var)      0
  62 #endif /* CONFIG_SCHEDSTATS */
  63
  64 #ifdef CONFIG_SCHED_INFO
  65 static inline void sched_info_reset_dequeued(struct task_struct *t)
  66 {
  67         t->sched_info.last_queued = 0;
  68 }
  69
  70 /*
  71  * We are interested in knowing how long it was from the *first* time a
  72  * task was queued to the time that it finally hit a cpu, we call this routine
  73  * from dequeue_task() to account for possible rq->clock skew across cpus. The
  74  * delta taken on each cpu would annul the skew.
  75  */
  76 static inline void sched_info_dequeued(struct rq *rq, struct task_struct *t)
  77 {
  78         unsigned long long now = rq_clock(rq), delta = 0;
  79
  80         if (unlikely(sched_info_on()))
  81                 if (t->sched_info.last_queued)
  82                         delta = now - t->sched_info.last_queued;
  83         sched_info_reset_dequeued(t);
  84         t->sched_info.run_delay += delta;
  85
  86         rq_sched_info_dequeued(rq, delta);
  87 }
  88
  89 /*
  90  * Called when a task finally hits the cpu.  We can now calculate how
  91  * long it was waiting to run.  We also note when it began so that we
  92  * can keep stats on how long its timeslice is.
  93  */
  94 static void sched_info_arrive(struct rq *rq, struct task_struct *t)
  95 {
  96         unsigned long long now = rq_clock(rq), delta = 0;
  97
  98         if (t->sched_info.last_queued)
  99                 delta = now - t->sched_info.last_queued;
 100         sched_info_reset_dequeued(t);
 101         t->sched_info.run_delay += delta;
 102         t->sched_info.last_arrival = now;
 103         t->sched_info.pcount++;
 104
 105         rq_sched_info_arrive(rq, delta);
 106 }
 107
 108 /*
 109  * This function is only called from enqueue_task(), but also only updates
 110  * the timestamp if it is already not set.  It's assumed that
 111  * sched_info_dequeued() will clear that stamp when appropriate.
 112  */
 113 static inline void sched_info_queued(struct rq *rq, struct task_struct *t)
 114 {
 115         if (unlikely(sched_info_on()))
 116                 if (!t->sched_info.last_queued)
 117                         t->sched_info.last_queued = rq_clock(rq);
 118 }
 119
 120 /*
 121  * Called when a process ceases being the active-running process involuntarily
 122  * due, typically, to expiring its time slice (this may also be called when
 123  * switching to the idle task).  Now we can calculate how long we ran.
 124  * Also, if the process is still in the TASK_RUNNING state, call
 125  * sched_info_queued() to mark that it has now again started waiting on
 126  * the runqueue.
 127  */
 128 static inline void sched_info_depart(struct rq *rq, struct task_struct *t)
 129 {
 130         unsigned long long delta = rq_clock(rq) -
 131                                         t->sched_info.last_arrival;
 132
 133         rq_sched_info_depart(rq, delta);
 134
 135         if (t->state == TASK_RUNNING)
 136                 sched_info_queued(rq, t);
 137 }
 138
 139 /*
 140  * Called when tasks are switched involuntarily due, typically, to expiring
 141  * their time slice.  (This may also be called when switching to or from
 142  * the idle task.)  We are only called when prev != next.
 143  */
 144 static inline void
 145 __sched_info_switch(struct rq *rq,
 146                     struct task_struct *prev, struct task_struct *next)
 147 {
 148         /*
 149          * prev now departs the cpu.  It's not interesting to record
 150          * stats about how efficient we were at scheduling the idle
 151          * process, however.
 152          */
 153         if (prev != rq->idle)
 154                 sched_info_depart(rq, prev);
 155
 156         if (next != rq->idle)
 157                 sched_info_arrive(rq, next);
 158 }
 159 static inline void
 160 sched_info_switch(struct rq *rq,
 161                   struct task_struct *prev, struct task_struct *next)
 162 {
 163         if (unlikely(sched_info_on()))
 164                 __sched_info_switch(rq, prev, next);
 165 }
 166 #else
 167 #define sched_info_queued(rq, t)                do { } while (0)
 168 #define sched_info_reset_dequeued(t)    do { } while (0)
 169 #define sched_info_dequeued(rq, t)              do { } while (0)
 170 #define sched_info_depart(rq, t)                do { } while (0)
 171 #define sched_info_arrive(rq, next)             do { } while (0)
 172 #define sched_info_switch(rq, t, next)          do { } while (0)
 173 #endif /* CONFIG_SCHED_INFO */