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