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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Per Entity Load Tracking
  *
  *  Copyright (C) 2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
  *
  *  Interactivity improvements by Mike Galbraith
  *  (C) 2007 Mike Galbraith <efault@gmx.de>
  *
  *  Various enhancements by Dmitry Adamushko.
  *  (C) 2007 Dmitry Adamushko <dmitry.adamushko@gmail.com>
  *
  *  Group scheduling enhancements by Srivatsa Vaddagiri
  *  Copyright IBM Corporation, 2007
  *  Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
  *
  *  Scaled math optimizations by Thomas Gleixner
  *  Copyright (C) 2007, Thomas Gleixner <tglx@linutronix.de>
  *
  *  Adaptive scheduling granularity, math enhancements by Peter Zijlstra
  *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
  *
  *  Move PELT related code from fair.c into this pelt.c file
  *  Author: Vincent Guittot <vincent.guittot@linaro.org>
  */
 
 /*
  * Approximate:
  *   val * y^n,    where y^32 ~= 0.5 (~1 scheduling period)
  */
 static u64 decay_load(u64 val, u64 n)
 {
     unsigned int local_n;
 
     if (unlikely(n > LOAD_AVG_PERIOD * 63))
         return 0;
 
     /* after bounds checking we can collapse to 32-bit */
     local_n = n;
 
     /*
      * As y^PERIOD = 1/2, we can combine
      *    y^n = 1/2^(n/PERIOD) * y^(n%PERIOD)
      * With a look-up table which covers y^n (n<PERIOD)
      *
      * To achieve constant time decay_load.
      */
     if (unlikely(local_n >= LOAD_AVG_PERIOD)) {
         val >>= local_n / LOAD_AVG_PERIOD;
         local_n %= LOAD_AVG_PERIOD;
     }
 
     val = mul_u64_u32_shr(val, runnable_avg_yN_inv[local_n], 32);
     return val;
 }
 
 static u32 __accumulate_pelt_segments(u64 periods, u32 d1, u32 d3)
 {
     u32 c1, c2, c3 = d3; /* y^0 == 1 */
 
     /*
      * c1 = d1 y^p
      */
     c1 = decay_load((u64)d1, periods);
 
     /*
      *            p-1
      * c2 = 1024 \Sum y^n
      *            n=1
      *
      *              inf        inf
      *    = 1024 ( \Sum y^n - \Sum y^n - y^0 )
      *              n=0        n=p
      */
     c2 = LOAD_AVG_MAX - decay_load(LOAD_AVG_MAX, periods) - 1024;
 
     return c1 + c2 + c3;
 }
 
 /*
  * Accumulate the three separate parts of the sum; d1 the remainder
  * of the last (incomplete) period, d2 the span of full periods and d3
  * the remainder of the (incomplete) current period.
  *
  *           d1          d2           d3
  *           ^           ^            ^
  *           |           |            |
  *         |<->|<----------------->|<--->|
  * ... |---x---|------| ... |------|-----x (now)
  *
  *                           p-1
  * u' = (u + d1) y^p + 1024 \Sum y^n + d3 y^0
  *                           n=1
  *
  *    = u y^p +                 (Step 1)
  *
  *                     p-1
  *      d1 y^p + 1024 \Sum y^n + d3 y^0     (Step 2)
  *                     n=1
  */
 static __always_inline u32
 accumulate_sum(u64 delta, struct sched_avg *sa,
            unsigned long load, unsigned long runnable, int running)
 {
     u32 contrib = (u32)delta; /* p == 0 -> delta < 1024 */
     u64 periods;
 
     delta += sa->period_contrib;
     periods = delta / 1024; /* A period is 1024us (~1ms) */
 
     /*
      * Step 1: decay old *_sum if we crossed period boundaries.
      */
     if (periods) {
         sa->load_sum = decay_load(sa->load_sum, periods);
         sa->runnable_sum =
             decay_load(sa->runnable_sum, periods);
         sa->util_sum = decay_load((u64)(sa->util_sum), periods);
 
         /*
          * Step 2
          */
         delta %= 1024;
         if (load) {
             /*
              * This relies on the:
              *
              * if (!load)
              *  runnable = running = 0;
              *
              * clause from ___update_load_sum(); this results in
              * the below usage of @contrib to disappear entirely,
              * so no point in calculating it.
              */
             contrib = __accumulate_pelt_segments(periods,
                     1024 - sa->period_contrib, delta);
         }
     }
     sa->period_contrib = delta;
 
     if (load)
         sa->load_sum += load * contrib;
     if (runnable)
         sa->runnable_sum += runnable * contrib << SCHED_CAPACITY_SHIFT;
     if (running)
         sa->util_sum += contrib << SCHED_CAPACITY_SHIFT;
 
     return periods;
 }
 
 /*
  * We can represent the historical contribution to runnable average as the
  * coefficients of a geometric series.  To do this we sub-divide our runnable
  * history into segments of approximately 1ms (1024us); label the segment that
  * occurred N-ms ago p_N, with p_0 corresponding to the current period, e.g.
  *
  * [<- 1024us ->|<- 1024us ->|<- 1024us ->| ...
  *      p0            p1           p2
  *     (now)       (~1ms ago)  (~2ms ago)
  *
  * Let u_i denote the fraction of p_i that the entity was runnable.
  *
  * We then designate the fractions u_i as our co-efficients, yielding the
  * following representation of historical load:
  *   u_0 + u_1*y + u_2*y^2 + u_3*y^3 + ...
  *
  * We choose y based on the with of a reasonably scheduling period, fixing:
  *   y^32 = 0.5
  *
  * This means that the contribution to load ~32ms ago (u_32) will be weighted
  * approximately half as much as the contribution to load within the last ms
  * (u_0).
  *
  * When a period "rolls over" and we have new u_0`, multiplying the previous
  * sum again by y is sufficient to update:
  *   load_avg = u_0` + y*(u_0 + u_1*y + u_2*y^2 + ... )
  *            = u_0 + u_1*y + u_2*y^2 + ... [re-labeling u_i --> u_{i+1}]
  */
 static __always_inline int
 ___update_load_sum(u64 now, struct sched_avg *sa,
           unsigned long load, unsigned long runnable, int running)
 {
     u64 delta;
 
     delta = now - sa->last_update_time;
     /*
      * This should only happen when time goes backwards, which it
      * unfortunately does during sched clock init when we swap over to TSC.
      */
     if ((s64)delta < 0) {
         sa->last_update_time = now;
         return 0;
     }
 
     /*
      * Use 1024ns as the unit of measurement since it's a reasonable
      * approximation of 1us and fast to compute.
      */
     delta >>= 10;
     if (!delta)
         return 0;
 
     sa->last_update_time += delta << 10;
 
     /*
      * running is a subset of runnable (weight) so running can't be set if
      * runnable is clear. But there are some corner cases where the current
      * se has been already dequeued but cfs_rq->curr still points to it.
      * This means that weight will be 0 but not running for a sched_entity
      * but also for a cfs_rq if the latter becomes idle. As an example,
      * this happens during idle_balance() which calls
      * update_blocked_averages().
      *
      * Also see the comment in accumulate_sum().
      */
     if (!load)
         runnable = running = 0;
 
     /*
      * Now we know we crossed measurement unit boundaries. The *_avg
      * accrues by two steps:
      *
      * Step 1: accumulate *_sum since last_update_time. If we haven't
      * crossed period boundaries, finish.
      */
     if (!accumulate_sum(delta, sa, load, runnable, running))
         return 0;
 
     return 1;
 }
 
 /*
  * When syncing *_avg with *_sum, we must take into account the current
  * position in the PELT segment otherwise the remaining part of the segment
  * will be considered as idle time whereas it's not yet elapsed and this will
  * generate unwanted oscillation in the range [1002..1024[.
  *
  * The max value of *_sum varies with the position in the time segment and is
  * equals to :
  *
  *   LOAD_AVG_MAX*y + sa->period_contrib
  *
  * which can be simplified into:
  *
  *   LOAD_AVG_MAX - 1024 + sa->period_contrib
  *
  * because LOAD_AVG_MAX*y == LOAD_AVG_MAX-1024
  *
  * The same care must be taken when a sched entity is added, updated or
  * removed from a cfs_rq and we need to update sched_avg. Scheduler entities
  * and the cfs rq, to which they are attached, have the same position in the
  * time segment because they use the same clock. This means that we can use
  * the period_contrib of cfs_rq when updating the sched_avg of a sched_entity
  * if it's more convenient.
  */
 static __always_inline void
 ___update_load_avg(struct sched_avg *sa, unsigned long load)
 {
     u32 divider = get_pelt_divider(sa);
 
     /*
      * Step 2: update *_avg.
      */
     sa->load_avg = div_u64(load * sa->load_sum, divider);
     sa->runnable_avg = div_u64(sa->runnable_sum, divider);
     WRITE_ONCE(sa->util_avg, sa->util_sum / divider);
 }
 
 /*
  * sched_entity:
  *
  *   task:
  *     se_weight()   = se->load.weight
  *     se_runnable() = !!on_rq
  *
  *   group: [ see update_cfs_group() ]
  *     se_weight()   = tg->weight * grq->load_avg / tg->load_avg
  *     se_runnable() = grq->h_nr_running
  *
  *   runnable_sum = se_runnable() * runnable = grq->runnable_sum
  *   runnable_avg = runnable_sum
  *
  *   load_sum := runnable
  *   load_avg = se_weight(se) * load_sum
  *
  * cfq_rq:
  *
  *   runnable_sum = \Sum se->avg.runnable_sum
  *   runnable_avg = \Sum se->avg.runnable_avg
  *
  *   load_sum = \Sum se_weight(se) * se->avg.load_sum
  *   load_avg = \Sum se->avg.load_avg
  */
 
 int __update_load_avg_blocked_se(u64 now, struct sched_entity *se)
 {
     if (___update_load_sum(now, &se->avg, 0, 0, 0)) {
         ___update_load_avg(&se->avg, se_weight(se));
         trace_pelt_se_tp(se);
         return 1;
     }
 
     return 0;
 }
 
 int __update_load_avg_se(u64 now, struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
     if (___update_load_sum(now, &se->avg, !!se->on_rq, se_runnable(se),
                 cfs_rq->curr == se)) {
 
         ___update_load_avg(&se->avg, se_weight(se));
         cfs_se_util_change(&se->avg);
         trace_pelt_se_tp(se);
         return 1;
     }
 
     return 0;
 }
 
 int __update_load_avg_cfs_rq(u64 now, struct cfs_rq *cfs_rq)
 {
     if (___update_load_sum(now, &cfs_rq->avg,
                 scale_load_down(cfs_rq->load.weight),
                 cfs_rq->h_nr_running,
                 cfs_rq->curr != NULL)) {
 
         ___update_load_avg(&cfs_rq->avg, 1);
         trace_pelt_cfs_tp(cfs_rq);
         return 1;
     }
 
     return 0;
 }
 
 /*
  * rt_rq:
  *
  *   util_sum = \Sum se->avg.util_sum but se->avg.util_sum is not tracked
  *   util_sum = cpu_scale * load_sum
  *   runnable_sum = util_sum
  *
  *   load_avg and runnable_avg are not supported and meaningless.
  *
  */
 
 int update_rt_rq_load_avg(u64 now, struct rq *rq, int running)
 {
     if (___update_load_sum(now, &rq->avg_rt,
                 running,
                 running,
                 running)) {
 
         ___update_load_avg(&rq->avg_rt, 1);
         trace_pelt_rt_tp(rq);
         return 1;
     }
 
     return 0;
 }
 
 /*
  * dl_rq:
  *
  *   util_sum = \Sum se->avg.util_sum but se->avg.util_sum is not tracked
  *   util_sum = cpu_scale * load_sum
  *   runnable_sum = util_sum
  *
  *   load_avg and runnable_avg are not supported and meaningless.
  *
  */
 
 int update_dl_rq_load_avg(u64 now, struct rq *rq, int running)
 {
     if (___update_load_sum(now, &rq->avg_dl,
                 running,
                 running,
                 running)) {
 
         ___update_load_avg(&rq->avg_dl, 1);
         trace_pelt_dl_tp(rq);
         return 1;
     }
 
     return 0;
 }
 
 #ifdef CONFIG_SCHED_THERMAL_PRESSURE
 /*
  * thermal:
  *
  *   load_sum = \Sum se->avg.load_sum but se->avg.load_sum is not tracked
  *
  *   util_avg and runnable_load_avg are not supported and meaningless.
  *
  * Unlike rt/dl utilization tracking that track time spent by a cpu
  * running a rt/dl task through util_avg, the average thermal pressure is
  * tracked through load_avg. This is because thermal pressure signal is
  * time weighted "delta" capacity unlike util_avg which is binary.
  * "delta capacity" =  actual capacity  -
  *          capped capacity a cpu due to a thermal event.
  */
 
 int update_thermal_load_avg(u64 now, struct rq *rq, u64 capacity)
 {
     if (___update_load_sum(now, &rq->avg_thermal,
                    capacity,
                    capacity,
                    capacity)) {
         ___update_load_avg(&rq->avg_thermal, 1);
         trace_pelt_thermal_tp(rq);
         return 1;
     }
 
     return 0;
 }
 #endif
 
 #ifdef CONFIG_HAVE_SCHED_AVG_IRQ
 /*
  * irq:
  *
  *   util_sum = \Sum se->avg.util_sum but se->avg.util_sum is not tracked
  *   util_sum = cpu_scale * load_sum
  *   runnable_sum = util_sum
  *
  *   load_avg and runnable_avg are not supported and meaningless.
  *
  */
 
 int update_irq_load_avg(struct rq *rq, u64 running)
 {
     int ret = 0;
 
     /*
      * We can't use clock_pelt because irq time is not accounted in
      * clock_task. Instead we directly scale the running time to
      * reflect the real amount of computation
      */
     running = cap_scale(running, arch_scale_freq_capacity(cpu_of(rq)));
     running = cap_scale(running, arch_scale_cpu_capacity(cpu_of(rq)));
 
     /*
      * We know the time that has been used by interrupt since last update
      * but we don't when. Let be pessimistic and assume that interrupt has
      * happened just before the update. This is not so far from reality
      * because interrupt will most probably wake up task and trig an update
      * of rq clock during which the metric is updated.
      * We start to decay with normal context time and then we add the
      * interrupt context time.
      * We can safely remove running from rq->clock because
      * rq->clock += delta with delta >= running
      */
     ret = ___update_load_sum(rq->clock - running, &rq->avg_irq,
                 0,
                 0,
                 0);
     ret += ___update_load_sum(rq->clock, &rq->avg_irq,
                 1,
                 1,
                 1);
 
     if (ret) {
         ___update_load_avg(&rq->avg_irq, 1);
         trace_pelt_irq_tp(rq);
     }
 
     return ret;
 }
 #endif

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