kernel/sched/stats.h

   1
   2 #ifdef CONFIG_SCHEDSTATS
   3
   4 /*
   5  * Expects runqueue lock to be held for atomicity of update
   6  */
   7 static inline void
   8 rq_sched_info_arrive(struct rq *rq, unsigned long long delta)
   9 {
  10         if (rq) {
  11                 rq->rq_sched_info.run_delay += delta;
  12                 rq->rq_sched_info.pcount++;
  13         }
  14 }
  15
  16 /*
  17  * Expects runqueue lock to be held for atomicity of update
  18  */
  19 static inline void
  20 rq_sched_info_depart(struct rq *rq, unsigned long long delta)
  21 {
  22         if (rq)
  23                 rq->rq_cpu_time += delta;
  24 }
  25
  26 static inline void
  27 rq_sched_info_dequeued(struct rq *rq, unsigned long long delta)
  28 {
  29         if (rq)
  30                 rq->rq_sched_info.run_delay += delta;
  31 }
  32 #define schedstat_enabled()             static_branch_unlikely(&sched_schedstats)
  33 #define schedstat_inc(var)              do { if (schedstat_enabled()) { var++; } } while (0)
  34 #define schedstat_add(var, amt)         do { if (schedstat_enabled()) { var += (amt); } } while (0)
  35 #define schedstat_set(var, val)         do { if (schedstat_enabled()) { var = (val); } } while (0)
  36 #define schedstat_val(var)              ((schedstat_enabled()) ? (var) : 0)
  37
  38 #else /* !CONFIG_SCHEDSTATS */
  39 static inline void
  40 rq_sched_info_arrive(struct rq *rq, unsigned long long delta)
  41 {}
  42 static inline void
  43 rq_sched_info_dequeued(struct rq *rq, unsigned long long delta)
  44 {}
  45 static inline void
  46 rq_sched_info_depart(struct rq *rq, unsigned long long delta)
  47 {}
  48 #define schedstat_enabled()             0
  49 #define schedstat_inc(var)              do { } while (0)
  50 #define schedstat_add(var, amt)         do { } while (0)
  51 #define schedstat_set(var, val)         do { } while (0)
  52 #define schedstat_val(var)              0
  53 #endif /* CONFIG_SCHEDSTATS */
  54
  55 #ifdef CONFIG_SCHED_INFO
  56 static inline void sched_info_reset_dequeued(struct task_struct *t)
  57 {
  58         t->sched_info.last_queued = 0;
  59 }
  60
  61 /*
  62  * We are interested in knowing how long it was from the *first* time a
  63  * task was queued to the time that it finally hit a cpu, we call this routine
  64  * from dequeue_task() to account for possible rq->clock skew across cpus. The
  65  * delta taken on each cpu would annul the skew.
  66  */
  67 static inline void sched_info_dequeued(struct rq *rq, struct task_struct *t)
  68 {
  69         unsigned long long now = rq_clock(rq), delta = 0;
  70
  71         if (unlikely(sched_info_on()))
  72                 if (t->sched_info.last_queued)
  73                         delta = now - t->sched_info.last_queued;
  74         sched_info_reset_dequeued(t);
  75         t->sched_info.run_delay += delta;
  76
  77         rq_sched_info_dequeued(rq, delta);
  78 }
  79
  80 /*
  81  * Called when a task finally hits the cpu.  We can now calculate how
  82  * long it was waiting to run.  We also note when it began so that we
  83  * can keep stats on how long its timeslice is.
  84  */
  85 static void sched_info_arrive(struct rq *rq, struct task_struct *t)
  86 {
  87         unsigned long long now = rq_clock(rq), delta = 0;
  88
  89         if (t->sched_info.last_queued)
  90                 delta = now - t->sched_info.last_queued;
  91         sched_info_reset_dequeued(t);
  92         t->sched_info.run_delay += delta;
  93         t->sched_info.last_arrival = now;
  94         t->sched_info.pcount++;
  95
  96         rq_sched_info_arrive(rq, delta);
  97 }
  98
  99 /*
 100  * This function is only called from enqueue_task(), but also only updates
 101  * the timestamp if it is already not set.  It's assumed that
 102  * sched_info_dequeued() will clear that stamp when appropriate.
 103  */
 104 static inline void sched_info_queued(struct rq *rq, struct task_struct *t)
 105 {
 106         if (unlikely(sched_info_on()))
 107                 if (!t->sched_info.last_queued)
 108                         t->sched_info.last_queued = rq_clock(rq);
 109 }
 110
 111 /*
 112  * Called when a process ceases being the active-running process involuntarily
 113  * due, typically, to expiring its time slice (this may also be called when
 114  * switching to the idle task).  Now we can calculate how long we ran.
 115  * Also, if the process is still in the TASK_RUNNING state, call
 116  * sched_info_queued() to mark that it has now again started waiting on
 117  * the runqueue.
 118  */
 119 static inline void sched_info_depart(struct rq *rq, struct task_struct *t)
 120 {
 121         unsigned long long delta = rq_clock(rq) -
 122                                         t->sched_info.last_arrival;
 123
 124         rq_sched_info_depart(rq, delta);
 125
 126         if (t->state == TASK_RUNNING)
 127                 sched_info_queued(rq, t);
 128 }
 129
 130 /*
 131  * Called when tasks are switched involuntarily due, typically, to expiring
 132  * their time slice.  (This may also be called when switching to or from
 133  * the idle task.)  We are only called when prev != next.
 134  */
 135 static inline void
 136 __sched_info_switch(struct rq *rq,
 137                     struct task_struct *prev, struct task_struct *next)
 138 {
 139         /*
 140          * prev now departs the cpu.  It's not interesting to record
 141          * stats about how efficient we were at scheduling the idle
 142          * process, however.
 143          */
 144         if (prev != rq->idle)
 145                 sched_info_depart(rq, prev);
 146
 147         if (next != rq->idle)
 148                 sched_info_arrive(rq, next);
 149 }
 150 static inline void
 151 sched_info_switch(struct rq *rq,
 152                   struct task_struct *prev, struct task_struct *next)
 153 {
 154         if (unlikely(sched_info_on()))
 155                 __sched_info_switch(rq, prev, next);
 156 }
 157 #else
 158 #define sched_info_queued(rq, t)                do { } while (0)
 159 #define sched_info_reset_dequeued(t)    do { } while (0)
 160 #define sched_info_dequeued(rq, t)              do { } while (0)
 161 #define sched_info_depart(rq, t)                do { } while (0)
 162 #define sched_info_arrive(rq, next)             do { } while (0)
 163 #define sched_info_switch(rq, t, next)          do { } while (0)
 164 #endif /* CONFIG_SCHED_INFO */
 165
 166 /*
 167  * The following are functions that support scheduler-internal time accounting.
 168  * These functions are generally called at the timer tick.  None of this depends
 169  * on CONFIG_SCHEDSTATS.
 170  */
 171
 172 /**
 173  * cputimer_running - return true if cputimer is running
 174  *
 175  * @tsk:        Pointer to target task.
 176  */
 177 static inline bool cputimer_running(struct task_struct *tsk)
 178
 179 {
 180         struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
 181
 182         /* Check if cputimer isn't running. This is accessed without locking. */
 183         if (!READ_ONCE(cputimer->running))
 184                 return false;
 185
 186         /*
 187          * After we flush the task's sum_exec_runtime to sig->sum_sched_runtime
 188          * in __exit_signal(), we won't account to the signal struct further
 189          * cputime consumed by that task, even though the task can still be
 190          * ticking after __exit_signal().
 191          *
 192          * In order to keep a consistent behaviour between thread group cputime
 193          * and thread group cputimer accounting, lets also ignore the cputime
 194          * elapsing after __exit_signal() in any thread group timer running.
 195          *
 196          * This makes sure that POSIX CPU clocks and timers are synchronized, so
 197          * that a POSIX CPU timer won't expire while the corresponding POSIX CPU
 198          * clock delta is behind the expiring timer value.
 199          */
 200         if (unlikely(!tsk->sighand))
 201                 return false;
 202
 203         return true;
 204 }
 205
 206 /**
 207  * account_group_user_time - Maintain utime for a thread group.
 208  *
 209  * @tsk:        Pointer to task structure.
 210  * @cputime:    Time value by which to increment the utime field of the
 211  *              thread_group_cputime structure.
 212  *
 213  * If thread group time is being maintained, get the structure for the
 214  * running CPU and update the utime field there.
 215  */
 216 static inline void account_group_user_time(struct task_struct *tsk,
 217                                            cputime_t cputime)
 218 {
 219         struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
 220
 221         if (!cputimer_running(tsk))
 222                 return;
 223
 224         atomic64_add(cputime, &cputimer->cputime_atomic.utime);
 225 }
 226
 227 /**
 228  * account_group_system_time - Maintain stime for a thread group.
 229  *
 230  * @tsk:        Pointer to task structure.
 231  * @cputime:    Time value by which to increment the stime field of the
 232  *              thread_group_cputime structure.
 233  *
 234  * If thread group time is being maintained, get the structure for the
 235  * running CPU and update the stime field there.
 236  */
 237 static inline void account_group_system_time(struct task_struct *tsk,
 238                                              cputime_t cputime)
 239 {
 240         struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
 241
 242         if (!cputimer_running(tsk))
 243                 return;
 244
 245         atomic64_add(cputime, &cputimer->cputime_atomic.stime);
 246 }
 247
 248 /**
 249  * account_group_exec_runtime - Maintain exec runtime for a thread group.
 250  *
 251  * @tsk:        Pointer to task structure.
 252  * @ns:         Time value by which to increment the sum_exec_runtime field
 253  *              of the thread_group_cputime structure.
 254  *
 255  * If thread group time is being maintained, get the structure for the
 256  * running CPU and update the sum_exec_runtime field there.
 257  */
 258 static inline void account_group_exec_runtime(struct task_struct *tsk,
 259                                               unsigned long long ns)
 260 {
 261         struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
 262
 263         if (!cputimer_running(tsk))
 264                 return;
 265
 266         atomic64_add(ns, &cputimer->cputime_atomic.sum_exec_runtime);
 267 }