linux/kernel/sched/pelt.h
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   1#ifdef CONFIG_SMP
   2#include "sched-pelt.h"
   3
   4int __update_load_avg_blocked_se(u64 now, struct sched_entity *se);
   5int __update_load_avg_se(u64 now, struct cfs_rq *cfs_rq, struct sched_entity *se);
   6int __update_load_avg_cfs_rq(u64 now, struct cfs_rq *cfs_rq);
   7int update_rt_rq_load_avg(u64 now, struct rq *rq, int running);
   8int update_dl_rq_load_avg(u64 now, struct rq *rq, int running);
   9
  10#ifdef CONFIG_HAVE_SCHED_AVG_IRQ
  11int update_irq_load_avg(struct rq *rq, u64 running);
  12#else
  13static inline int
  14update_irq_load_avg(struct rq *rq, u64 running)
  15{
  16        return 0;
  17}
  18#endif
  19
  20/*
  21 * When a task is dequeued, its estimated utilization should not be update if
  22 * its util_avg has not been updated at least once.
  23 * This flag is used to synchronize util_avg updates with util_est updates.
  24 * We map this information into the LSB bit of the utilization saved at
  25 * dequeue time (i.e. util_est.dequeued).
  26 */
  27#define UTIL_AVG_UNCHANGED 0x1
  28
  29static inline void cfs_se_util_change(struct sched_avg *avg)
  30{
  31        unsigned int enqueued;
  32
  33        if (!sched_feat(UTIL_EST))
  34                return;
  35
  36        /* Avoid store if the flag has been already set */
  37        enqueued = avg->util_est.enqueued;
  38        if (!(enqueued & UTIL_AVG_UNCHANGED))
  39                return;
  40
  41        /* Reset flag to report util_avg has been updated */
  42        enqueued &= ~UTIL_AVG_UNCHANGED;
  43        WRITE_ONCE(avg->util_est.enqueued, enqueued);
  44}
  45
  46/*
  47 * The clock_pelt scales the time to reflect the effective amount of
  48 * computation done during the running delta time but then sync back to
  49 * clock_task when rq is idle.
  50 *
  51 *
  52 * absolute time   | 1| 2| 3| 4| 5| 6| 7| 8| 9|10|11|12|13|14|15|16
  53 * @ max capacity  ------******---------------******---------------
  54 * @ half capacity ------************---------************---------
  55 * clock pelt      | 1| 2|    3|    4| 7| 8| 9|   10|   11|14|15|16
  56 *
  57 */
  58static inline void update_rq_clock_pelt(struct rq *rq, s64 delta)
  59{
  60        if (unlikely(is_idle_task(rq->curr))) {
  61                /* The rq is idle, we can sync to clock_task */
  62                rq->clock_pelt  = rq_clock_task(rq);
  63                return;
  64        }
  65
  66        /*
  67         * When a rq runs at a lower compute capacity, it will need
  68         * more time to do the same amount of work than at max
  69         * capacity. In order to be invariant, we scale the delta to
  70         * reflect how much work has been really done.
  71         * Running longer results in stealing idle time that will
  72         * disturb the load signal compared to max capacity. This
  73         * stolen idle time will be automatically reflected when the
  74         * rq will be idle and the clock will be synced with
  75         * rq_clock_task.
  76         */
  77
  78        /*
  79         * Scale the elapsed time to reflect the real amount of
  80         * computation
  81         */
  82        delta = cap_scale(delta, arch_scale_cpu_capacity(cpu_of(rq)));
  83        delta = cap_scale(delta, arch_scale_freq_capacity(cpu_of(rq)));
  84
  85        rq->clock_pelt += delta;
  86}
  87
  88/*
  89 * When rq becomes idle, we have to check if it has lost idle time
  90 * because it was fully busy. A rq is fully used when the /Sum util_sum
  91 * is greater or equal to:
  92 * (LOAD_AVG_MAX - 1024 + rq->cfs.avg.period_contrib) << SCHED_CAPACITY_SHIFT;
  93 * For optimization and computing rounding purpose, we don't take into account
  94 * the position in the current window (period_contrib) and we use the higher
  95 * bound of util_sum to decide.
  96 */
  97static inline void update_idle_rq_clock_pelt(struct rq *rq)
  98{
  99        u32 divider = ((LOAD_AVG_MAX - 1024) << SCHED_CAPACITY_SHIFT) - LOAD_AVG_MAX;
 100        u32 util_sum = rq->cfs.avg.util_sum;
 101        util_sum += rq->avg_rt.util_sum;
 102        util_sum += rq->avg_dl.util_sum;
 103
 104        /*
 105         * Reflecting stolen time makes sense only if the idle
 106         * phase would be present at max capacity. As soon as the
 107         * utilization of a rq has reached the maximum value, it is
 108         * considered as an always runnig rq without idle time to
 109         * steal. This potential idle time is considered as lost in
 110         * this case. We keep track of this lost idle time compare to
 111         * rq's clock_task.
 112         */
 113        if (util_sum >= divider)
 114                rq->lost_idle_time += rq_clock_task(rq) - rq->clock_pelt;
 115}
 116
 117static inline u64 rq_clock_pelt(struct rq *rq)
 118{
 119        lockdep_assert_held(&rq->lock);
 120        assert_clock_updated(rq);
 121
 122        return rq->clock_pelt - rq->lost_idle_time;
 123}
 124
 125#ifdef CONFIG_CFS_BANDWIDTH
 126/* rq->task_clock normalized against any time this cfs_rq has spent throttled */
 127static inline u64 cfs_rq_clock_pelt(struct cfs_rq *cfs_rq)
 128{
 129        if (unlikely(cfs_rq->throttle_count))
 130                return cfs_rq->throttled_clock_task - cfs_rq->throttled_clock_task_time;
 131
 132        return rq_clock_pelt(rq_of(cfs_rq)) - cfs_rq->throttled_clock_task_time;
 133}
 134#else
 135static inline u64 cfs_rq_clock_pelt(struct cfs_rq *cfs_rq)
 136{
 137        return rq_clock_pelt(rq_of(cfs_rq));
 138}
 139#endif
 140
 141#else
 142
 143static inline int
 144update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq)
 145{
 146        return 0;
 147}
 148
 149static inline int
 150update_rt_rq_load_avg(u64 now, struct rq *rq, int running)
 151{
 152        return 0;
 153}
 154
 155static inline int
 156update_dl_rq_load_avg(u64 now, struct rq *rq, int running)
 157{
 158        return 0;
 159}
 160
 161static inline int
 162update_irq_load_avg(struct rq *rq, u64 running)
 163{
 164        return 0;
 165}
 166
 167static inline u64 rq_clock_pelt(struct rq *rq)
 168{
 169        return rq_clock_task(rq);
 170}
 171
 172static inline void
 173update_rq_clock_pelt(struct rq *rq, s64 delta) { }
 174
 175static inline void
 176update_idle_rq_clock_pelt(struct rq *rq) { }
 177
 178#endif
 179
 180
 181