1 files changed, 469 insertions, 0 deletions

diff --git a/kernel/sched/pelt.c b/kernel/sched/pelt.c
new file mode 100644
index 0000000000..0f31076826
--- /dev/null
+++ b/kernel/sched/pelt.c
@@ -0,0 +1,469 @@
+// 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