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Date: Tue, 23 Jun 2015 18:30:48 +0800
From: Wanpeng Li <wanpeng.li@...mail.com>
To: Yuyang Du <yuyang.du@...el.com>, mingo@...nel.org,
peterz@...radead.org, linux-kernel@...r.kernel.org
CC: pjt@...gle.com, bsegall@...gle.com, morten.rasmussen@....com,
vincent.guittot@...aro.org, dietmar.eggemann@....com,
len.brown@...el.com, rafael.j.wysocki@...el.com,
fengguang.wu@...el.com, boqun.feng@...il.com,
srikar@...ux.vnet.ibm.com
Subject: Re: [PATCH v9 2/4] sched: Rewrite runnable load and utilization
average tracking
On 6/23/15 8:08 AM, Yuyang Du wrote:
> The idea of runnable load average (let runnable time contribute to weight)
> was proposed by Paul Turner, and it is still followed by this rewrite. This
> rewrite aims to solve the following issues:
>
> 1. cfs_rq's load average (namely runnable_load_avg and blocked_load_avg) is
> updated at the granularity of an entity at a time, which results in the
> cfs_rq's load average is stale or partially updated: at any time, only
> one entity is up to date, all other entities are effectively lagging
> behind. This is undesirable.
>
> To illustrate, if we have n runnable entities in the cfs_rq, as time
> elapses, they certainly become outdated:
>
> t0: cfs_rq { e1_old, e2_old, ..., en_old }
>
> and when we update:
>
> t1: update e1, then we have cfs_rq { e1_new, e2_old, ..., en_old }
>
> t2: update e2, then we have cfs_rq { e1_old, e2_new, ..., en_old }
>
> ...
>
> We solve this by combining all runnable entities' load averages together
> in cfs_rq's avg, and update the cfs_rq's avg as a whole. This is based
> on the fact that if we regard the update as a function, then:
>
> w * update(e) = update(w * e) and
>
> update(e1) + update(e2) = update(e1 + e2), then
>
> w1 * update(e1) + w2 * update(e2) = update(w1 * e1 + w2 * e2)
>
> therefore, by this rewrite, we have an entirely updated cfs_rq at the
> time we update it:
>
> t1: update cfs_rq { e1_new, e2_new, ..., en_new }
>
> t2: update cfs_rq { e1_new, e2_new, ..., en_new }
>
> ...
>
> 2. cfs_rq's load average is different between top rq->cfs_rq and other
> task_group's per CPU cfs_rqs in whether or not blocked_load_average
> contributes to the load.
>
> The basic idea behind runnable load average (the same for utilization)
> is that the blocked state is taken into account as opposed to only
> accounting for the currently runnable state. Therefore, the average
> should include both the runnable/running and blocked load averages.
> This rewrite does that.
>
> In addition, we also combine runnable/running and blocked averages
> of all entities into the cfs_rq's average, and update it together at
> once. This is based on the fact that:
>
> update(runnable) + update(blocked) = update(runnable + blocked)
>
> This significantly reduces the codes as we don't need to separately
> maintain/update runnable/running load and blocked load.
>
> 3. How task_group entities' share is calculated is complex and imprecise.
>
> We reduce the complexity in this rewrite to allow a very simple rule:
> the task_group's load_avg is aggregated from its per CPU cfs_rqs's
> load_avgs. Then group entity's weight is simply proportional to its
> own cfs_rq's load_avg / task_group's load_avg. To illustrate,
>
> if a task_group has { cfs_rq1, cfs_rq2, ..., cfs_rqn }, then,
>
> task_group_avg = cfs_rq1_avg + cfs_rq2_avg + ... + cfs_rqn_avg, then
>
> cfs_rqx's entity's share = cfs_rqx_avg / task_group_avg * task_group's share
>
> To sum up, this rewrite in principle is equivalent to the current one, but
> fixes the issues described above. Turns out, it significantly reduces the
> code complexity and hence increases clarity and efficiency. In addition,
> the new averages are more smooth/continuous (no spurious spikes and valleys)
> and updated more consistently and quickly to reflect the load dynamics. As a
> result, we have less load tracking overhead, better performance, and
> especially better power efficiency due to more balanced load.
>
> Signed-off-by: Yuyang Du <yuyang.du@...el.com>
> ---
> include/linux/sched.h | 40 ++--
> kernel/sched/core.c | 3 -
> kernel/sched/debug.c | 41 ++--
> kernel/sched/fair.c | 630 +++++++++++++++++---------------------------------
> kernel/sched/sched.h | 28 +--
> 5 files changed, 249 insertions(+), 493 deletions(-)
>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index af0eeba..8b4bc4f 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -1183,29 +1183,23 @@ struct load_weight {
> u32 inv_weight;
> };
>
> +/*
> + * The load_avg/util_avg represents an infinite geometric series:
> + * 1) load_avg describes the amount of time that a sched_entity
> + * is runnable on a rq. It is based on both load_sum and the
> + * weight of the task.
> + * 2) util_avg describes the amount of time that a sched_entity
> + * is running on a CPU. It is based on util_sum and is scaled
> + * in the range [0..SCHED_LOAD_SCALE].
> + * The 64 bit load_sum can:
> + * 1) for cfs_rq, afford 4353082796 (=2^64/47742/88761) entities with
> + * the highest weight (=88761) always runnable, we should not overflow
> + * 2) for entity, support any load.weight always runnable
> + */
> struct sched_avg {
> - u64 last_runnable_update;
> - s64 decay_count;
> - /*
> - * utilization_avg_contrib describes the amount of time that a
> - * sched_entity is running on a CPU. It is based on running_avg_sum
> - * and is scaled in the range [0..SCHED_LOAD_SCALE].
> - * load_avg_contrib described the amount of time that a sched_entity
> - * is runnable on a rq. It is based on both runnable_avg_sum and the
> - * weight of the task.
> - */
> - unsigned long load_avg_contrib, utilization_avg_contrib;
> - /*
> - * These sums represent an infinite geometric series and so are bound
> - * above by 1024/(1-y). Thus we only need a u32 to store them for all
> - * choices of y < 1-2^(-32)*1024.
> - * running_avg_sum reflects the time that the sched_entity is
> - * effectively running on the CPU.
> - * runnable_avg_sum represents the amount of time a sched_entity is on
> - * a runqueue which includes the running time that is monitored by
> - * running_avg_sum.
> - */
> - u32 runnable_avg_sum, avg_period, running_avg_sum;
> + u64 last_update_time, load_sum;
> + u32 util_sum, period_contrib;
> + unsigned long load_avg, util_avg;
> };
>
> #ifdef CONFIG_SCHEDSTATS
> @@ -1271,7 +1265,7 @@ struct sched_entity {
> #endif
>
> #ifdef CONFIG_SMP
> - /* Per-entity load-tracking */
> + /* Per entity load average tracking */
> struct sched_avg avg;
> #endif
> };
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index d5078c0..4dfab27 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -1828,9 +1828,6 @@ static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
> p->se.prev_sum_exec_runtime = 0;
> p->se.nr_migrations = 0;
> p->se.vruntime = 0;
> -#ifdef CONFIG_SMP
> - p->se.avg.decay_count = 0;
> -#endif
> INIT_LIST_HEAD(&p->se.group_node);
>
> #ifdef CONFIG_SCHEDSTATS
> diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
> index ca39cb7..56d83f3 100644
> --- a/kernel/sched/debug.c
> +++ b/kernel/sched/debug.c
> @@ -88,12 +88,8 @@ static void print_cfs_group_stats(struct seq_file *m, int cpu, struct task_group
> #endif
> P(se->load.weight);
> #ifdef CONFIG_SMP
> - P(se->avg.runnable_avg_sum);
> - P(se->avg.running_avg_sum);
> - P(se->avg.avg_period);
> - P(se->avg.load_avg_contrib);
> - P(se->avg.utilization_avg_contrib);
> - P(se->avg.decay_count);
> + P(se->avg.load_avg);
> + P(se->avg.util_avg);
> #endif
> #undef PN
> #undef P
> @@ -207,21 +203,19 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
> SEQ_printf(m, " .%-30s: %d\n", "nr_running", cfs_rq->nr_running);
> SEQ_printf(m, " .%-30s: %ld\n", "load", cfs_rq->load.weight);
> #ifdef CONFIG_SMP
> - SEQ_printf(m, " .%-30s: %ld\n", "runnable_load_avg",
> - cfs_rq->runnable_load_avg);
> - SEQ_printf(m, " .%-30s: %ld\n", "blocked_load_avg",
> - cfs_rq->blocked_load_avg);
> - SEQ_printf(m, " .%-30s: %ld\n", "utilization_load_avg",
> - cfs_rq->utilization_load_avg);
> + SEQ_printf(m, " .%-30s: %lu\n", "load_avg",
> + cfs_rq->avg.load_avg);
> + SEQ_printf(m, " .%-30s: %lu\n", "util_avg",
> + cfs_rq->avg.util_avg);
> + SEQ_printf(m, " .%-30s: %ld\n", "removed_load_avg",
> + atomic_long_read(&cfs_rq->removed_load_avg));
> + SEQ_printf(m, " .%-30s: %ld\n", "removed_util_avg",
> + atomic_long_read(&cfs_rq->removed_util_avg));
> #ifdef CONFIG_FAIR_GROUP_SCHED
> - SEQ_printf(m, " .%-30s: %ld\n", "tg_load_contrib",
> - cfs_rq->tg_load_contrib);
> - SEQ_printf(m, " .%-30s: %d\n", "tg_runnable_contrib",
> - cfs_rq->tg_runnable_contrib);
> + SEQ_printf(m, " .%-30s: %lu\n", "tg_load_avg_contrib",
> + cfs_rq->tg_load_avg_contrib);
> SEQ_printf(m, " .%-30s: %ld\n", "tg_load_avg",
> atomic_long_read(&cfs_rq->tg->load_avg));
> - SEQ_printf(m, " .%-30s: %d\n", "tg->runnable_avg",
> - atomic_read(&cfs_rq->tg->runnable_avg));
> #endif
> #endif
> #ifdef CONFIG_CFS_BANDWIDTH
> @@ -632,12 +626,11 @@ void proc_sched_show_task(struct task_struct *p, struct seq_file *m)
>
> P(se.load.weight);
> #ifdef CONFIG_SMP
> - P(se.avg.runnable_avg_sum);
> - P(se.avg.running_avg_sum);
> - P(se.avg.avg_period);
> - P(se.avg.load_avg_contrib);
> - P(se.avg.utilization_avg_contrib);
> - P(se.avg.decay_count);
> + P(se.avg.load_sum);
> + P(se.avg.util_sum);
> + P(se.avg.load_avg);
> + P(se.avg.util_avg);
> + P(se.avg.last_update_time);
> #endif
> P(policy);
> P(prio);
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 7922532..452c932 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -283,9 +283,6 @@ static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
> return grp->my_q;
> }
>
> -static void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq,
> - int force_update);
> -
> static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
> {
> if (!cfs_rq->on_list) {
> @@ -305,8 +302,6 @@ static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
> }
>
> cfs_rq->on_list = 1;
> - /* We should have no load, but we need to update last_decay. */
> - update_cfs_rq_blocked_load(cfs_rq, 0);
> }
> }
>
> @@ -669,19 +664,31 @@ static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se)
> static int select_idle_sibling(struct task_struct *p, int cpu);
> static unsigned long task_h_load(struct task_struct *p);
>
> -static inline void __update_task_entity_contrib(struct sched_entity *se);
> -static inline void __update_task_entity_utilization(struct sched_entity *se);
> +/*
> + * We choose a half-life close to 1 scheduling period.
> + * Note: The tables below are dependent on this value.
> + */
> +#define LOAD_AVG_PERIOD 32
> +#define LOAD_AVG_MAX 47742 /* maximum possible load avg */
> +#define LOAD_AVG_MAX_N 345 /* number of full periods to produce LOAD_MAX_AVG */
>
> /* Give new task start runnable values to heavy its load in infant time */
> void init_task_runnable_average(struct task_struct *p)
> {
> - u32 slice;
> + struct sched_avg *sa = &p->se.avg;
>
> - slice = sched_slice(task_cfs_rq(p), &p->se) >> 10;
> - p->se.avg.runnable_avg_sum = p->se.avg.running_avg_sum = slice;
> - p->se.avg.avg_period = slice;
> - __update_task_entity_contrib(&p->se);
> - __update_task_entity_utilization(&p->se);
> + sa->last_update_time = 0;
> + /*
> + * sched_avg's period_contrib should be strictly less then 1024, so
> + * we give it 1023 to make sure it is almost a period (1024us), and
> + * will definitely be update (after enqueue).
> + */
> + sa->period_contrib = 1023;
> + sa->load_avg = scale_load_down(p->se.load.weight);
> + sa->load_sum = sa->load_avg * LOAD_AVG_MAX;
> + sa->util_avg = scale_load_down(SCHED_LOAD_SCALE);
> + sa->util_sum = LOAD_AVG_MAX;
> + /* when this task enqueue'ed, it will contribute to its cfs_rq's load_avg */
> }
> #else
> void init_task_runnable_average(struct task_struct *p)
> @@ -1702,8 +1709,8 @@ static u64 numa_get_avg_runtime(struct task_struct *p, u64 *period)
> delta = runtime - p->last_sum_exec_runtime;
> *period = now - p->last_task_numa_placement;
> } else {
> - delta = p->se.avg.runnable_avg_sum;
> - *period = p->se.avg.avg_period;
> + delta = p->se.avg.load_sum / p->se.load.weight;
> + *period = LOAD_AVG_MAX;
> }
>
> p->last_sum_exec_runtime = runtime;
> @@ -2351,13 +2358,13 @@ static inline long calc_tg_weight(struct task_group *tg, struct cfs_rq *cfs_rq)
> long tg_weight;
>
> /*
> - * Use this CPU's actual weight instead of the last load_contribution
> - * to gain a more accurate current total weight. See
> - * update_cfs_rq_load_contribution().
> + * Use this CPU's real-time load instead of the last load contribution
> + * as the updating of the contribution is delayed, and we will use the
> + * the real-time load to calc the share. See update_tg_load_avg().
> */
> tg_weight = atomic_long_read(&tg->load_avg);
> - tg_weight -= cfs_rq->tg_load_contrib;
> - tg_weight += cfs_rq->load.weight;
> + tg_weight -= cfs_rq->tg_load_avg_contrib;
> + tg_weight += cfs_rq->avg.load_avg;
>
> return tg_weight;
> }
> @@ -2367,7 +2374,7 @@ static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
> long tg_weight, load, shares;
>
> tg_weight = calc_tg_weight(tg, cfs_rq);
> - load = cfs_rq->load.weight;
> + load = cfs_rq->avg.load_avg;
>
> shares = (tg->shares * load);
> if (tg_weight)
> @@ -2429,14 +2436,6 @@ static inline void update_cfs_shares(struct cfs_rq *cfs_rq)
> #endif /* CONFIG_FAIR_GROUP_SCHED */
>
> #ifdef CONFIG_SMP
> -/*
> - * We choose a half-life close to 1 scheduling period.
> - * Note: The tables below are dependent on this value.
> - */
> -#define LOAD_AVG_PERIOD 32
> -#define LOAD_AVG_MAX 47742 /* maximum possible load avg */
> -#define LOAD_AVG_MAX_N 345 /* number of full periods to produce LOAD_MAX_AVG */
> -
> /* Precomputed fixed inverse multiplies for multiplication by y^n */
> static const u32 runnable_avg_yN_inv[] = {
> 0xffffffff, 0xfa83b2da, 0xf5257d14, 0xefe4b99a, 0xeac0c6e6, 0xe5b906e6,
> @@ -2485,9 +2484,8 @@ static __always_inline u64 decay_load(u64 val, u64 n)
> local_n %= LOAD_AVG_PERIOD;
> }
>
> - val *= runnable_avg_yN_inv[local_n];
> - /* We don't use SRR here since we always want to round down. */
> - return val >> 32;
> + val = mul_u64_u32_shr(val, runnable_avg_yN_inv[local_n], 32);
> + return val;
> }
>
> /*
> @@ -2546,23 +2544,23 @@ static u32 __compute_runnable_contrib(u64 n)
> * 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_entity_runnable_avg(u64 now, int cpu,
> - struct sched_avg *sa,
> - int runnable,
> - int running)
> +static __always_inline int __update_load_avg(u64 now, int cpu,
> + struct sched_avg *sa,
> + unsigned long weight,
> + int running)
> {
> u64 delta, periods;
> - u32 runnable_contrib;
> + u32 contrib;
> int delta_w, decayed = 0;
> unsigned long scale_freq = arch_scale_freq_capacity(NULL, cpu);
>
> - delta = now - sa->last_runnable_update;
> + 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_runnable_update = now;
> + sa->last_update_time = now;
> return 0;
> }
>
> @@ -2573,26 +2571,26 @@ static __always_inline int __update_entity_runnable_avg(u64 now, int cpu,
> delta >>= 10;
> if (!delta)
> return 0;
> - sa->last_runnable_update = now;
> + sa->last_update_time = now;
>
> /* delta_w is the amount already accumulated against our next period */
> - delta_w = sa->avg_period % 1024;
> + delta_w = sa->period_contrib;
> if (delta + delta_w >= 1024) {
> - /* period roll-over */
> decayed = 1;
>
> + /* how much left for next period will start over, we don't know yet */
> + sa->period_contrib = 0;
> +
> /*
> * Now that we know we're crossing a period boundary, figure
> * out how much from delta we need to complete the current
> * period and accrue it.
> */
> delta_w = 1024 - delta_w;
> - if (runnable)
> - sa->runnable_avg_sum += delta_w;
> + if (weight)
> + sa->load_sum += weight * delta_w;
> if (running)
> - sa->running_avg_sum += delta_w * scale_freq
> - >> SCHED_CAPACITY_SHIFT;
> - sa->avg_period += delta_w;
> + sa->util_sum += delta_w * scale_freq >> SCHED_CAPACITY_SHIFT;
>
> delta -= delta_w;
>
> @@ -2600,334 +2598,156 @@ static __always_inline int __update_entity_runnable_avg(u64 now, int cpu,
> periods = delta / 1024;
> delta %= 1024;
>
> - sa->runnable_avg_sum = decay_load(sa->runnable_avg_sum,
> - periods + 1);
> - sa->running_avg_sum = decay_load(sa->running_avg_sum,
> - periods + 1);
> - sa->avg_period = decay_load(sa->avg_period,
> - periods + 1);
> + sa->load_sum = decay_load(sa->load_sum, periods + 1);
> + sa->util_sum = decay_load((u64)(sa->util_sum), periods + 1);
>
> /* Efficiently calculate \sum (1..n_period) 1024*y^i */
> - runnable_contrib = __compute_runnable_contrib(periods);
> - if (runnable)
> - sa->runnable_avg_sum += runnable_contrib;
> + contrib = __compute_runnable_contrib(periods);
> + if (weight)
> + sa->load_sum += weight * contrib;
> if (running)
> - sa->running_avg_sum += runnable_contrib * scale_freq
> - >> SCHED_CAPACITY_SHIFT;
> - sa->avg_period += runnable_contrib;
> + sa->util_sum += contrib * scale_freq >> SCHED_CAPACITY_SHIFT;
> }
>
> /* Remainder of delta accrued against u_0` */
> - if (runnable)
> - sa->runnable_avg_sum += delta;
> + if (weight)
> + sa->load_sum += weight * delta;
> if (running)
> - sa->running_avg_sum += delta * scale_freq
> - >> SCHED_CAPACITY_SHIFT;
> - sa->avg_period += delta;
> -
> - return decayed;
> -}
> -
> -/* Synchronize an entity's decay with its parenting cfs_rq.*/
> -static inline u64 __synchronize_entity_decay(struct sched_entity *se)
> -{
> - struct cfs_rq *cfs_rq = cfs_rq_of(se);
> - u64 decays = atomic64_read(&cfs_rq->decay_counter);
> + sa->util_sum += delta * scale_freq >> SCHED_CAPACITY_SHIFT;
>
> - decays -= se->avg.decay_count;
> - se->avg.decay_count = 0;
> - if (!decays)
> - return 0;
> + sa->period_contrib += delta;
>
> - se->avg.load_avg_contrib = decay_load(se->avg.load_avg_contrib, decays);
> - se->avg.utilization_avg_contrib =
> - decay_load(se->avg.utilization_avg_contrib, decays);
> + if (decayed) {
> + sa->load_avg = div_u64(sa->load_sum, LOAD_AVG_MAX);
> + sa->util_avg = (sa->util_sum << SCHED_LOAD_SHIFT) / LOAD_AVG_MAX;
> + }
>
> - return decays;
> + return decayed;
> }
>
> #ifdef CONFIG_FAIR_GROUP_SCHED
> -static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq,
> - int force_update)
> -{
> - struct task_group *tg = cfs_rq->tg;
> - long tg_contrib;
> -
> - tg_contrib = cfs_rq->runnable_load_avg + cfs_rq->blocked_load_avg;
> - tg_contrib -= cfs_rq->tg_load_contrib;
> -
> - if (!tg_contrib)
> - return;
> -
> - if (force_update || abs(tg_contrib) > cfs_rq->tg_load_contrib / 8) {
> - atomic_long_add(tg_contrib, &tg->load_avg);
> - cfs_rq->tg_load_contrib += tg_contrib;
> - }
> -}
> -
> /*
> - * Aggregate cfs_rq runnable averages into an equivalent task_group
> - * representation for computing load contributions.
> + * Updating tg's load_avg is necessary before update_cfs_share (which is done)
> + * and effective_load (which is not done because it is too costly).
> */
> -static inline void __update_tg_runnable_avg(struct sched_avg *sa,
> - struct cfs_rq *cfs_rq)
> +static inline void update_tg_load_avg(struct cfs_rq *cfs_rq, int force)
> {
> - struct task_group *tg = cfs_rq->tg;
> - long contrib;
> -
> - /* The fraction of a cpu used by this cfs_rq */
> - contrib = div_u64((u64)sa->runnable_avg_sum << NICE_0_SHIFT,
> - sa->avg_period + 1);
> - contrib -= cfs_rq->tg_runnable_contrib;
> + long delta = cfs_rq->avg.load_avg - cfs_rq->tg_load_avg_contrib;
>
> - if (abs(contrib) > cfs_rq->tg_runnable_contrib / 64) {
> - atomic_add(contrib, &tg->runnable_avg);
> - cfs_rq->tg_runnable_contrib += contrib;
> - }
> -}
> -
> -static inline void __update_group_entity_contrib(struct sched_entity *se)
> -{
> - struct cfs_rq *cfs_rq = group_cfs_rq(se);
> - struct task_group *tg = cfs_rq->tg;
> - int runnable_avg;
> -
> - u64 contrib;
> -
> - contrib = cfs_rq->tg_load_contrib * tg->shares;
> - se->avg.load_avg_contrib = div_u64(contrib,
> - atomic_long_read(&tg->load_avg) + 1);
> -
> - /*
> - * For group entities we need to compute a correction term in the case
> - * that they are consuming <1 cpu so that we would contribute the same
> - * load as a task of equal weight.
> - *
> - * Explicitly co-ordinating this measurement would be expensive, but
> - * fortunately the sum of each cpus contribution forms a usable
> - * lower-bound on the true value.
> - *
> - * Consider the aggregate of 2 contributions. Either they are disjoint
> - * (and the sum represents true value) or they are disjoint and we are
> - * understating by the aggregate of their overlap.
> - *
> - * Extending this to N cpus, for a given overlap, the maximum amount we
> - * understand is then n_i(n_i+1)/2 * w_i where n_i is the number of
> - * cpus that overlap for this interval and w_i is the interval width.
> - *
> - * On a small machine; the first term is well-bounded which bounds the
> - * total error since w_i is a subset of the period. Whereas on a
> - * larger machine, while this first term can be larger, if w_i is the
> - * of consequential size guaranteed to see n_i*w_i quickly converge to
> - * our upper bound of 1-cpu.
> - */
> - runnable_avg = atomic_read(&tg->runnable_avg);
> - if (runnable_avg < NICE_0_LOAD) {
> - se->avg.load_avg_contrib *= runnable_avg;
> - se->avg.load_avg_contrib >>= NICE_0_SHIFT;
> + if (force || abs(delta) > cfs_rq->tg_load_avg_contrib / 64) {
> + atomic_long_add(delta, &cfs_rq->tg->load_avg);
> + cfs_rq->tg_load_avg_contrib = cfs_rq->avg.load_avg;
> }
> }
>
> #else /* CONFIG_FAIR_GROUP_SCHED */
> -static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq,
> - int force_update) {}
> -static inline void __update_tg_runnable_avg(struct sched_avg *sa,
> - struct cfs_rq *cfs_rq) {}
> -static inline void __update_group_entity_contrib(struct sched_entity *se) {}
> +static inline void update_tg_load_avg(struct cfs_rq *cfs_rq, int force) {}
> #endif /* CONFIG_FAIR_GROUP_SCHED */
>
> -static inline void __update_task_entity_contrib(struct sched_entity *se)
> -{
> - u32 contrib;
> -
> - /* avoid overflowing a 32-bit type w/ SCHED_LOAD_SCALE */
> - contrib = se->avg.runnable_avg_sum * scale_load_down(se->load.weight);
> - contrib /= (se->avg.avg_period + 1);
> - se->avg.load_avg_contrib = scale_load(contrib);
> -}
> +static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq);
>
> -/* Compute the current contribution to load_avg by se, return any delta */
> -static long __update_entity_load_avg_contrib(struct sched_entity *se)
> +/* Group cfs_rq's load_avg is used for task_h_load and update_cfs_share */
> +static inline int update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq)
> {
> - long old_contrib = se->avg.load_avg_contrib;
> + int decayed;
> + struct sched_avg *sa = &cfs_rq->avg;
>
> - if (entity_is_task(se)) {
> - __update_task_entity_contrib(se);
> - } else {
> - __update_tg_runnable_avg(&se->avg, group_cfs_rq(se));
> - __update_group_entity_contrib(se);
> + if (atomic_long_read(&cfs_rq->removed_load_avg)) {
> + long r = atomic_long_xchg(&cfs_rq->removed_load_avg, 0);
> + sa->load_avg = max_t(long, sa->load_avg - r, 0);
> + sa->load_sum = max_t(s64, sa->load_sum - r * LOAD_AVG_MAX, 0);
> }
>
> - return se->avg.load_avg_contrib - old_contrib;
> -}
> -
> -
> -static inline void __update_task_entity_utilization(struct sched_entity *se)
> -{
> - u32 contrib;
> -
> - /* avoid overflowing a 32-bit type w/ SCHED_LOAD_SCALE */
> - contrib = se->avg.running_avg_sum * scale_load_down(SCHED_LOAD_SCALE);
> - contrib /= (se->avg.avg_period + 1);
> - se->avg.utilization_avg_contrib = scale_load(contrib);
> -}
> + if (atomic_long_read(&cfs_rq->removed_util_avg)) {
> + long r = atomic_long_xchg(&cfs_rq->removed_util_avg, 0);
> + sa->util_avg = max_t(long, sa->util_avg - r, 0);
> + sa->util_sum = max_t(s32, sa->util_sum -
> + ((r * LOAD_AVG_MAX) >> SCHED_LOAD_SHIFT), 0);
> + }
>
> -static long __update_entity_utilization_avg_contrib(struct sched_entity *se)
> -{
> - long old_contrib = se->avg.utilization_avg_contrib;
> + decayed = __update_load_avg(now, cpu_of(rq_of(cfs_rq)), sa,
> + scale_load_down(cfs_rq->load.weight), cfs_rq->curr != NULL);
>
> - if (entity_is_task(se))
> - __update_task_entity_utilization(se);
> - else
> - se->avg.utilization_avg_contrib =
> - group_cfs_rq(se)->utilization_load_avg;
> -
> - return se->avg.utilization_avg_contrib - old_contrib;
> -}
> +#ifndef CONFIG_64BIT
> + smp_wmb();
> + cfs_rq->load_last_update_time_copy = sa->last_update_time;
> +#endif
>
> -static inline void subtract_blocked_load_contrib(struct cfs_rq *cfs_rq,
> - long load_contrib)
> -{
> - if (likely(load_contrib < cfs_rq->blocked_load_avg))
> - cfs_rq->blocked_load_avg -= load_contrib;
> - else
> - cfs_rq->blocked_load_avg = 0;
> + return decayed;
> }
>
> -static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq);
> -
> -/* Update a sched_entity's runnable average */
> -static inline void update_entity_load_avg(struct sched_entity *se,
> - int update_cfs_rq)
> +/* Update task and its cfs_rq load average */
> +static inline void update_load_avg(struct sched_entity *se, int update_tg)
> {
> struct cfs_rq *cfs_rq = cfs_rq_of(se);
> - long contrib_delta, utilization_delta;
> int cpu = cpu_of(rq_of(cfs_rq));
> - u64 now;
> + u64 now = cfs_rq_clock_task(cfs_rq);
>
> /*
> - * For a group entity we need to use their owned cfs_rq_clock_task() in
> - * case they are the parent of a throttled hierarchy.
> + * Track task load average for carrying it to new CPU after migrated, and
> + * track group sched_entity load average for task_h_load calc in migration
> */
> - if (entity_is_task(se))
> - now = cfs_rq_clock_task(cfs_rq);
> - else
> - now = cfs_rq_clock_task(group_cfs_rq(se));
> + __update_load_avg(now, cpu, &se->avg,
> + se->on_rq * scale_load_down(se->load.weight), cfs_rq->curr == se);
>
> - if (!__update_entity_runnable_avg(now, cpu, &se->avg, se->on_rq,
> - cfs_rq->curr == se))
> - return;
> -
> - contrib_delta = __update_entity_load_avg_contrib(se);
> - utilization_delta = __update_entity_utilization_avg_contrib(se);
> -
> - if (!update_cfs_rq)
> - return;
> -
> - if (se->on_rq) {
> - cfs_rq->runnable_load_avg += contrib_delta;
> - cfs_rq->utilization_load_avg += utilization_delta;
> - } else {
> - subtract_blocked_load_contrib(cfs_rq, -contrib_delta);
> - }
> + if (update_cfs_rq_load_avg(now, cfs_rq) && update_tg)
> + update_tg_load_avg(cfs_rq, 0);
> }
>
> -/*
> - * Decay the load contributed by all blocked children and account this so that
> - * their contribution may appropriately discounted when they wake up.
> - */
> -static void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, int force_update)
> +/* Add the load generated by se into cfs_rq's load average */
> +static inline void
> +enqueue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
> {
> - u64 now = cfs_rq_clock_task(cfs_rq) >> 20;
> - u64 decays;
> -
> - decays = now - cfs_rq->last_decay;
> - if (!decays && !force_update)
> - return;
> + struct sched_avg *sa = &se->avg;
> + u64 now = cfs_rq_clock_task(cfs_rq);
> + int migrated = 0, decayed;
>
> - if (atomic_long_read(&cfs_rq->removed_load)) {
> - unsigned long removed_load;
> - removed_load = atomic_long_xchg(&cfs_rq->removed_load, 0);
> - subtract_blocked_load_contrib(cfs_rq, removed_load);
> + if (sa->last_update_time == 0) {
> + sa->last_update_time = now;
> + migrated = 1;
> }
> -
> - if (decays) {
> - cfs_rq->blocked_load_avg = decay_load(cfs_rq->blocked_load_avg,
> - decays);
> - atomic64_add(decays, &cfs_rq->decay_counter);
> - cfs_rq->last_decay = now;
> + else {
> + __update_load_avg(now, cpu_of(rq_of(cfs_rq)), sa,
> + se->on_rq * scale_load_down(se->load.weight), cfs_rq->curr == se);
> }
>
> - __update_cfs_rq_tg_load_contrib(cfs_rq, force_update);
> -}
> + decayed = update_cfs_rq_load_avg(now, cfs_rq);
>
> -/* Add the load generated by se into cfs_rq's child load-average */
> -static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq,
> - struct sched_entity *se,
> - int wakeup)
> -{
> - /*
> - * We track migrations using entity decay_count <= 0, on a wake-up
> - * migration we use a negative decay count to track the remote decays
> - * accumulated while sleeping.
> - *
> - * Newly forked tasks are enqueued with se->avg.decay_count == 0, they
> - * are seen by enqueue_entity_load_avg() as a migration with an already
> - * constructed load_avg_contrib.
> - */
> - if (unlikely(se->avg.decay_count <= 0)) {
> - se->avg.last_runnable_update = rq_clock_task(rq_of(cfs_rq));
> - if (se->avg.decay_count) {
> - /*
> - * In a wake-up migration we have to approximate the
> - * time sleeping. This is because we can't synchronize
> - * clock_task between the two cpus, and it is not
> - * guaranteed to be read-safe. Instead, we can
> - * approximate this using our carried decays, which are
> - * explicitly atomically readable.
> - */
> - se->avg.last_runnable_update -= (-se->avg.decay_count)
> - << 20;
> - update_entity_load_avg(se, 0);
> - /* Indicate that we're now synchronized and on-rq */
> - se->avg.decay_count = 0;
> - }
> - wakeup = 0;
> - } else {
> - __synchronize_entity_decay(se);
> + if (migrated) {
> + cfs_rq->avg.load_avg += sa->load_avg;
> + cfs_rq->avg.load_sum += sa->load_sum;
> + cfs_rq->avg.util_avg += sa->util_avg;
> + cfs_rq->avg.util_sum += sa->util_sum;
> }
>
> - /* migrated tasks did not contribute to our blocked load */
> - if (wakeup) {
> - subtract_blocked_load_contrib(cfs_rq, se->avg.load_avg_contrib);
> - update_entity_load_avg(se, 0);
> - }
> -
> - cfs_rq->runnable_load_avg += se->avg.load_avg_contrib;
> - cfs_rq->utilization_load_avg += se->avg.utilization_avg_contrib;
> - /* we force update consideration on load-balancer moves */
> - update_cfs_rq_blocked_load(cfs_rq, !wakeup);
> + if (decayed || migrated)
> + update_tg_load_avg(cfs_rq, 0);
> }
>
> /*
> - * Remove se's load from this cfs_rq child load-average, if the entity is
> - * transitioning to a blocked state we track its projected decay using
> - * blocked_load_avg.
> + * Task first catches up with cfs_rq, and then subtract
> + * itself from the cfs_rq (task must be off the queue now).
> */
> -static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq,
> - struct sched_entity *se,
> - int sleep)
> +void remove_entity_load_avg(struct sched_entity *se)
> {
> - update_entity_load_avg(se, 1);
> - /* we force update consideration on load-balancer moves */
> - update_cfs_rq_blocked_load(cfs_rq, !sleep);
> + struct cfs_rq *cfs_rq = cfs_rq_of(se);
> + u64 last_update_time;
> +
> +#ifndef CONFIG_64BIT
> + u64 last_update_time_copy;
>
> - cfs_rq->runnable_load_avg -= se->avg.load_avg_contrib;
> - cfs_rq->utilization_load_avg -= se->avg.utilization_avg_contrib;
> - if (sleep) {
> - cfs_rq->blocked_load_avg += se->avg.load_avg_contrib;
> - se->avg.decay_count = atomic64_read(&cfs_rq->decay_counter);
> - } /* migrations, e.g. sleep=0 leave decay_count == 0 */
> + do {
> + last_update_time_copy = cfs_rq->load_last_update_time_copy;
> + smp_rmb();
> + last_update_time = cfs_rq->avg.last_update_time;
> + } while (last_update_time != last_update_time_copy);
> +#else
> + last_update_time = cfs_rq->avg.last_update_time;
> +#endif
> +
> + __update_load_avg(last_update_time, cpu_of(rq_of(cfs_rq)), &se->avg, 0, 0);
> + atomic_long_add(se->avg.load_avg, &cfs_rq->removed_load_avg);
> + atomic_long_add(se->avg.util_avg, &cfs_rq->removed_util_avg);
> }
>
> /*
> @@ -2952,16 +2772,10 @@ static int idle_balance(struct rq *this_rq);
>
> #else /* CONFIG_SMP */
>
> -static inline void update_entity_load_avg(struct sched_entity *se,
> - int update_cfs_rq) {}
> -static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq,
> - struct sched_entity *se,
> - int wakeup) {}
> -static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq,
> - struct sched_entity *se,
> - int sleep) {}
> -static inline void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq,
> - int force_update) {}
> +static inline void update_load_avg(struct sched_entity *se, int update_tg) {}
> +static inline void
> +enqueue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
> +static inline void remove_entity_load_avg(struct sched_entity *se) {}
>
> static inline int idle_balance(struct rq *rq)
> {
> @@ -3093,7 +2907,7 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
> * Update run-time statistics of the 'current'.
> */
> update_curr(cfs_rq);
> - enqueue_entity_load_avg(cfs_rq, se, flags & ENQUEUE_WAKEUP);
> + enqueue_entity_load_avg(cfs_rq, se);
> account_entity_enqueue(cfs_rq, se);
> update_cfs_shares(cfs_rq);
>
> @@ -3168,7 +2982,7 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
> * Update run-time statistics of the 'current'.
> */
> update_curr(cfs_rq);
> - dequeue_entity_load_avg(cfs_rq, se, flags & DEQUEUE_SLEEP);
> + update_load_avg(se, 1);
>
> update_stats_dequeue(cfs_rq, se);
> if (flags & DEQUEUE_SLEEP) {
> @@ -3258,7 +3072,7 @@ set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
> */
> update_stats_wait_end(cfs_rq, se);
> __dequeue_entity(cfs_rq, se);
> - update_entity_load_avg(se, 1);
> + update_load_avg(se, 1);
> }
>
> update_stats_curr_start(cfs_rq, se);
> @@ -3358,7 +3172,7 @@ static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
> /* Put 'current' back into the tree. */
> __enqueue_entity(cfs_rq, prev);
> /* in !on_rq case, update occurred at dequeue */
> - update_entity_load_avg(prev, 1);
> + update_load_avg(prev, 0);
> }
> cfs_rq->curr = NULL;
> }
> @@ -3374,8 +3188,7 @@ entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
> /*
> * Ensure that runnable average is periodically updated.
> */
> - update_entity_load_avg(curr, 1);
> - update_cfs_rq_blocked_load(cfs_rq, 1);
> + update_load_avg(curr, 1);
> update_cfs_shares(cfs_rq);
>
> #ifdef CONFIG_SCHED_HRTICK
> @@ -4248,8 +4061,8 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
> if (cfs_rq_throttled(cfs_rq))
> break;
>
> + update_load_avg(se, 1);
> update_cfs_shares(cfs_rq);
> - update_entity_load_avg(se, 1);
> }
>
> if (!se)
> @@ -4308,8 +4121,8 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
> if (cfs_rq_throttled(cfs_rq))
> break;
>
> + update_load_avg(se, 1);
> update_cfs_shares(cfs_rq);
> - update_entity_load_avg(se, 1);
> }
>
> if (!se)
> @@ -4448,7 +4261,7 @@ static void __update_cpu_load(struct rq *this_rq, unsigned long this_load,
> static void update_idle_cpu_load(struct rq *this_rq)
> {
> unsigned long curr_jiffies = READ_ONCE(jiffies);
> - unsigned long load = this_rq->cfs.runnable_load_avg;
> + unsigned long load = this_rq->cfs.avg.load_avg;
> unsigned long pending_updates;
>
> /*
> @@ -4494,7 +4307,7 @@ void update_cpu_load_nohz(void)
> */
> void update_cpu_load_active(struct rq *this_rq)
> {
> - unsigned long load = this_rq->cfs.runnable_load_avg;
> + unsigned long load = this_rq->cfs.avg.load_avg;
How about using encapsulation weighted_cpuload() here to indicate
rq->cpu_load[] which don't care jitter use weighted cpuload directly.
Regards,
Wanpeng Li
> /*
> * See the mess around update_idle_cpu_load() / update_cpu_load_nohz().
> */
> @@ -4505,7 +4318,7 @@ void update_cpu_load_active(struct rq *this_rq)
> /* Used instead of source_load when we know the type == 0 */
> static unsigned long weighted_cpuload(const int cpu)
> {
> - return cpu_rq(cpu)->cfs.runnable_load_avg;
> + return cpu_rq(cpu)->cfs.avg.load_avg;
> }
>
> /*
> @@ -4555,7 +4368,7 @@ static unsigned long cpu_avg_load_per_task(int cpu)
> {
> struct rq *rq = cpu_rq(cpu);
> unsigned long nr_running = READ_ONCE(rq->cfs.h_nr_running);
> - unsigned long load_avg = rq->cfs.runnable_load_avg;
> + unsigned long load_avg = rq->cfs.avg.load_avg;
>
> if (nr_running)
> return load_avg / nr_running;
> @@ -4674,7 +4487,7 @@ static long effective_load(struct task_group *tg, int cpu, long wl, long wg)
> /*
> * w = rw_i + @wl
> */
> - w = se->my_q->load.weight + wl;
> + w = se->my_q->avg.load_avg + wl;
>
> /*
> * wl = S * s'_i; see (2)
> @@ -4695,7 +4508,7 @@ static long effective_load(struct task_group *tg, int cpu, long wl, long wg)
> /*
> * wl = dw_i = S * (s'_i - s_i); see (3)
> */
> - wl -= se->load.weight;
> + wl -= se->avg.load_avg;
>
> /*
> * Recursively apply this logic to all parent groups to compute
> @@ -4769,14 +4582,14 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
> */
> if (sync) {
> tg = task_group(current);
> - weight = current->se.load.weight;
> + weight = current->se.avg.load_avg;
>
> this_load += effective_load(tg, this_cpu, -weight, -weight);
> load += effective_load(tg, prev_cpu, 0, -weight);
> }
>
> tg = task_group(p);
> - weight = p->se.load.weight;
> + weight = p->se.avg.load_avg;
>
> /*
> * In low-load situations, where prev_cpu is idle and this_cpu is idle
> @@ -4969,12 +4782,12 @@ done:
> * tasks. The unit of the return value must be the one of capacity so we can
> * compare the usage with the capacity of the CPU that is available for CFS
> * task (ie cpu_capacity).
> - * cfs.utilization_load_avg is the sum of running time of runnable tasks on a
> + * cfs.avg.util_avg is the sum of running time of runnable tasks on a
> * CPU. It represents the amount of utilization of a CPU in the range
> * [0..SCHED_LOAD_SCALE]. The usage of a CPU can't be higher than the full
> * capacity of the CPU because it's about the running time on this CPU.
> - * Nevertheless, cfs.utilization_load_avg can be higher than SCHED_LOAD_SCALE
> - * because of unfortunate rounding in avg_period and running_load_avg or just
> + * Nevertheless, cfs.avg.util_avg can be higher than SCHED_LOAD_SCALE
> + * because of unfortunate rounding in util_avg or just
> * after migrating tasks until the average stabilizes with the new running
> * time. So we need to check that the usage stays into the range
> * [0..cpu_capacity_orig] and cap if necessary.
> @@ -4983,7 +4796,7 @@ done:
> */
> static int get_cpu_usage(int cpu)
> {
> - unsigned long usage = cpu_rq(cpu)->cfs.utilization_load_avg;
> + unsigned long usage = cpu_rq(cpu)->cfs.avg.util_avg;
> unsigned long capacity = capacity_orig_of(cpu);
>
> if (usage >= SCHED_LOAD_SCALE)
> @@ -5089,26 +4902,22 @@ unlock:
> * previous cpu. However, the caller only guarantees p->pi_lock is held; no
> * other assumptions, including the state of rq->lock, should be made.
> */
> -static void
> -migrate_task_rq_fair(struct task_struct *p, int next_cpu)
> +static void migrate_task_rq_fair(struct task_struct *p, int next_cpu)
> {
> - struct sched_entity *se = &p->se;
> - struct cfs_rq *cfs_rq = cfs_rq_of(se);
> -
> /*
> - * Load tracking: accumulate removed load so that it can be processed
> - * when we next update owning cfs_rq under rq->lock. Tasks contribute
> - * to blocked load iff they have a positive decay-count. It can never
> - * be negative here since on-rq tasks have decay-count == 0.
> + * We are supposed to update the task to "current" time, then its up to date
> + * and ready to go to new CPU/cfs_rq. But we have difficulty in getting
> + * what current time is, so simply throw away the out-of-date time. This
> + * will result in the wakee task is less decayed, but giving the wakee more
> + * load sounds not bad.
> */
> - if (se->avg.decay_count) {
> - se->avg.decay_count = -__synchronize_entity_decay(se);
> - atomic_long_add(se->avg.load_avg_contrib,
> - &cfs_rq->removed_load);
> - }
> + remove_entity_load_avg(&p->se);
> +
> + /* Tell new CPU we are migrated */
> + p->se.avg.last_update_time = 0;
>
> /* We have migrated, no longer consider this task hot */
> - se->exec_start = 0;
> + p->se.exec_start = 0;
> }
> #endif /* CONFIG_SMP */
>
> @@ -5995,36 +5804,6 @@ static void attach_tasks(struct lb_env *env)
> }
>
> #ifdef CONFIG_FAIR_GROUP_SCHED
> -/*
> - * update tg->load_weight by folding this cpu's load_avg
> - */
> -static void __update_blocked_averages_cpu(struct task_group *tg, int cpu)
> -{
> - struct sched_entity *se = tg->se[cpu];
> - struct cfs_rq *cfs_rq = tg->cfs_rq[cpu];
> -
> - /* throttled entities do not contribute to load */
> - if (throttled_hierarchy(cfs_rq))
> - return;
> -
> - update_cfs_rq_blocked_load(cfs_rq, 1);
> -
> - if (se) {
> - update_entity_load_avg(se, 1);
> - /*
> - * We pivot on our runnable average having decayed to zero for
> - * list removal. This generally implies that all our children
> - * have also been removed (modulo rounding error or bandwidth
> - * control); however, such cases are rare and we can fix these
> - * at enqueue.
> - *
> - * TODO: fix up out-of-order children on enqueue.
> - */
> - if (!se->avg.runnable_avg_sum && !cfs_rq->nr_running)
> - list_del_leaf_cfs_rq(cfs_rq);
> - }
> -}
> -
> static void update_blocked_averages(int cpu)
> {
> struct rq *rq = cpu_rq(cpu);
> @@ -6033,17 +5812,18 @@ static void update_blocked_averages(int cpu)
>
> raw_spin_lock_irqsave(&rq->lock, flags);
> update_rq_clock(rq);
> +
> /*
> * Iterates the task_group tree in a bottom up fashion, see
> * list_add_leaf_cfs_rq() for details.
> */
> for_each_leaf_cfs_rq(rq, cfs_rq) {
> - /*
> - * Note: We may want to consider periodically releasing
> - * rq->lock about these updates so that creating many task
> - * groups does not result in continually extending hold time.
> - */
> - __update_blocked_averages_cpu(cfs_rq->tg, rq->cpu);
> + /* throttled entities do not contribute to load */
> + if (throttled_hierarchy(cfs_rq))
> + continue;
> +
> + if (update_cfs_rq_load_avg(cfs_rq_clock_task(cfs_rq), cfs_rq))
> + update_tg_load_avg(cfs_rq, 0);
> }
>
> raw_spin_unlock_irqrestore(&rq->lock, flags);
> @@ -6073,14 +5853,13 @@ static void update_cfs_rq_h_load(struct cfs_rq *cfs_rq)
> }
>
> if (!se) {
> - cfs_rq->h_load = cfs_rq->runnable_load_avg;
> + cfs_rq->h_load = cfs_rq->avg.load_avg;
> cfs_rq->last_h_load_update = now;
> }
>
> while ((se = cfs_rq->h_load_next) != NULL) {
> load = cfs_rq->h_load;
> - load = div64_ul(load * se->avg.load_avg_contrib,
> - cfs_rq->runnable_load_avg + 1);
> + load = div64_ul(load * se->avg.load_avg, cfs_rq->avg.load_avg + 1);
> cfs_rq = group_cfs_rq(se);
> cfs_rq->h_load = load;
> cfs_rq->last_h_load_update = now;
> @@ -6092,8 +5871,8 @@ static unsigned long task_h_load(struct task_struct *p)
> struct cfs_rq *cfs_rq = task_cfs_rq(p);
>
> update_cfs_rq_h_load(cfs_rq);
> - return div64_ul(p->se.avg.load_avg_contrib * cfs_rq->h_load,
> - cfs_rq->runnable_load_avg + 1);
> + return div64_ul(p->se.avg.load_avg * cfs_rq->h_load,
> + cfs_rq->avg.load_avg + 1);
> }
> #else
> static inline void update_blocked_averages(int cpu)
> @@ -6102,7 +5881,7 @@ static inline void update_blocked_averages(int cpu)
>
> static unsigned long task_h_load(struct task_struct *p)
> {
> - return p->se.avg.load_avg_contrib;
> + return p->se.avg.load_avg;
> }
> #endif
>
> @@ -8103,15 +7882,18 @@ static void switched_from_fair(struct rq *rq, struct task_struct *p)
> }
>
> #ifdef CONFIG_SMP
> - /*
> - * Remove our load from contribution when we leave sched_fair
> - * and ensure we don't carry in an old decay_count if we
> - * switch back.
> - */
> - if (se->avg.decay_count) {
> - __synchronize_entity_decay(se);
> - subtract_blocked_load_contrib(cfs_rq, se->avg.load_avg_contrib);
> - }
> + /* Catch up with the cfs_rq and remove our load when we leave */
> + __update_load_avg(cfs_rq->avg.last_update_time, cpu_of(rq), &se->avg,
> + se->on_rq * scale_load_down(se->load.weight), cfs_rq->curr == se);
> +
> + cfs_rq->avg.load_avg =
> + max_t(long, cfs_rq->avg.load_avg - se->avg.load_avg, 0);
> + cfs_rq->avg.load_sum =
> + max_t(s64, cfs_rq->avg.load_sum - se->avg.load_sum, 0);
> + cfs_rq->avg.util_avg =
> + max_t(long, cfs_rq->avg.util_avg - se->avg.util_avg, 0);
> + cfs_rq->avg.util_sum =
> + max_t(s32, cfs_rq->avg.util_sum - se->avg.util_sum, 0);
> #endif
> }
>
> @@ -8168,8 +7950,8 @@ void init_cfs_rq(struct cfs_rq *cfs_rq)
> cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime;
> #endif
> #ifdef CONFIG_SMP
> - atomic64_set(&cfs_rq->decay_counter, 1);
> - atomic_long_set(&cfs_rq->removed_load, 0);
> + atomic_long_set(&cfs_rq->removed_load_avg, 0);
> + atomic_long_set(&cfs_rq->removed_util_avg, 0);
> #endif
> }
>
> @@ -8214,14 +7996,14 @@ static void task_move_group_fair(struct task_struct *p, int queued)
> if (!queued) {
> cfs_rq = cfs_rq_of(se);
> se->vruntime += cfs_rq->min_vruntime;
> +
> #ifdef CONFIG_SMP
> - /*
> - * migrate_task_rq_fair() will have removed our previous
> - * contribution, but we must synchronize for ongoing future
> - * decay.
> - */
> - se->avg.decay_count = atomic64_read(&cfs_rq->decay_counter);
> - cfs_rq->blocked_load_avg += se->avg.load_avg_contrib;
> + /* Virtually synchronize task with its new cfs_rq */
> + p->se.avg.last_update_time = cfs_rq->avg.last_update_time;
> + cfs_rq->avg.load_avg += p->se.avg.load_avg;
> + cfs_rq->avg.load_sum += p->se.avg.load_sum;
> + cfs_rq->avg.util_avg += p->se.avg.util_avg;
> + cfs_rq->avg.util_sum += p->se.avg.util_sum;
> #endif
> }
> }
> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> index d465a5c..3dfec8d 100644
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -245,7 +245,6 @@ struct task_group {
>
> #ifdef CONFIG_SMP
> atomic_long_t load_avg;
> - atomic_t runnable_avg;
> #endif
> #endif
>
> @@ -366,27 +365,18 @@ struct cfs_rq {
>
> #ifdef CONFIG_SMP
> /*
> - * CFS Load tracking
> - * Under CFS, load is tracked on a per-entity basis and aggregated up.
> - * This allows for the description of both thread and group usage (in
> - * the FAIR_GROUP_SCHED case).
> - * runnable_load_avg is the sum of the load_avg_contrib of the
> - * sched_entities on the rq.
> - * blocked_load_avg is similar to runnable_load_avg except that its
> - * the blocked sched_entities on the rq.
> - * utilization_load_avg is the sum of the average running time of the
> - * sched_entities on the rq.
> + * CFS load tracking
> */
> - unsigned long runnable_load_avg, blocked_load_avg, utilization_load_avg;
> - atomic64_t decay_counter;
> - u64 last_decay;
> - atomic_long_t removed_load;
> -
> + struct sched_avg avg;
> #ifdef CONFIG_FAIR_GROUP_SCHED
> - /* Required to track per-cpu representation of a task_group */
> - u32 tg_runnable_contrib;
> - unsigned long tg_load_contrib;
> + unsigned long tg_load_avg_contrib;
> +#endif
> + atomic_long_t removed_load_avg, removed_util_avg;
> +#ifndef CONFIG_64BIT
> + u64 load_last_update_time_copy;
> +#endif
>
> +#ifdef CONFIG_FAIR_GROUP_SCHED
> /*
> * h_load = weight * f(tg)
> *
--
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