* Adaptive scheduling granularity, math enhancements by Peter Zijlstra
* Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
*/
-
-#include <linux/sched/mm.h>
-#include <linux/sched/topology.h>
-
-#include <linux/latencytop.h>
-#include <linux/cpumask.h>
-#include <linux/cpuidle.h>
-#include <linux/slab.h>
-#include <linux/profile.h>
-#include <linux/interrupt.h>
-#include <linux/mempolicy.h>
-#include <linux/migrate.h>
-#include <linux/task_work.h>
-#include <linux/sched/isolation.h>
+#include "sched.h"
#include <trace/events/sched.h>
-#include "sched.h"
-
/*
* Targeted preemption latency for CPU-bound tasks:
*
#ifdef CONFIG_SMP
/*
- * For asym packing, by default the lower numbered cpu has higher priority.
+ * For asym packing, by default the lower numbered CPU has higher priority.
*/
int __weak arch_asym_cpu_priority(int cpu)
{
* For !fair tasks do:
*
update_cfs_rq_load_avg(now, cfs_rq);
- attach_entity_load_avg(cfs_rq, se);
+ attach_entity_load_avg(cfs_rq, se, 0);
switched_from_fair(rq, p);
*
* such that the next switched_to_fair() has the
}
/*
- * The averaged statistics, shared & private, memory & cpu,
+ * The averaged statistics, shared & private, memory & CPU,
* occupy the first half of the array. The second half of the
* array is for current counters, which are averaged into the
* first set by task_numa_placement.
* be incurred if the tasks were swapped.
*/
if (cur) {
- /* Skip this swap candidate if cannot move to the source cpu */
+ /* Skip this swap candidate if cannot move to the source CPU: */
if (!cpumask_test_cpu(env->src_cpu, &cur->cpus_allowed))
goto unlock;
goto balance;
}
- /* Balance doesn't matter much if we're running a task per cpu */
+ /* Balance doesn't matter much if we're running a task per CPU: */
if (imp > env->best_imp && src_rq->nr_running == 1 &&
dst_rq->nr_running == 1)
goto assign;
*/
if (!cur) {
/*
- * select_idle_siblings() uses an per-cpu cpumask that
+ * select_idle_siblings() uses an per-CPU cpumask that
* can be used from IRQ context.
*/
local_irq_disable();
static void numa_migrate_preferred(struct task_struct *p)
{
unsigned long interval = HZ;
+ unsigned long numa_migrate_retry;
/* This task has no NUMA fault statistics yet */
if (unlikely(p->numa_preferred_nid == -1 || !p->numa_faults))
/* Periodically retry migrating the task to the preferred node */
interval = min(interval, msecs_to_jiffies(p->numa_scan_period) / 16);
- p->numa_migrate_retry = jiffies + interval;
+ numa_migrate_retry = jiffies + interval;
+
+ /*
+ * Check that the new retry threshold is after the current one. If
+ * the retry is in the future, it implies that wake_affine has
+ * temporarily asked NUMA balancing to backoff from placement.
+ */
+ if (numa_migrate_retry > p->numa_migrate_retry)
+ return;
+
+ /* Safe to try placing the task on the preferred node */
+ p->numa_migrate_retry = numa_migrate_retry;
/* Success if task is already running on preferred CPU */
if (task_node(p) == p->numa_preferred_nid)
}
#ifdef CONFIG_FAIR_GROUP_SCHED
-# ifdef CONFIG_SMP
+#ifdef CONFIG_SMP
/*
* All this does is approximate the hierarchical proportion which includes that
* global sum we all love to hate.
return clamp_t(long, runnable, MIN_SHARES, shares);
}
-# endif /* CONFIG_SMP */
+#endif /* CONFIG_SMP */
static inline int throttled_hierarchy(struct cfs_rq *cfs_rq);
}
#endif /* CONFIG_FAIR_GROUP_SCHED */
-static inline void cfs_rq_util_change(struct cfs_rq *cfs_rq)
+static inline void cfs_rq_util_change(struct cfs_rq *cfs_rq, int flags)
{
struct rq *rq = rq_of(cfs_rq);
- if (&rq->cfs == cfs_rq) {
+ if (&rq->cfs == cfs_rq || (flags & SCHED_CPUFREQ_MIGRATION)) {
/*
* There are a few boundary cases this might miss but it should
* get called often enough that that should (hopefully) not be
*
* See cpu_util().
*/
- cpufreq_update_util(rq, 0);
+ cpufreq_update_util(rq, flags);
}
}
sa->util_avg = sa->util_sum / divider;
}
+/*
+ * When a task is dequeued, its estimated utilization should not be update if
+ * its util_avg has not been updated at least once.
+ * This flag is used to synchronize util_avg updates with util_est updates.
+ * We map this information into the LSB bit of the utilization saved at
+ * dequeue time (i.e. util_est.dequeued).
+ */
+#define UTIL_AVG_UNCHANGED 0x1
+
+static inline void cfs_se_util_change(struct sched_avg *avg)
+{
+ unsigned int enqueued;
+
+ if (!sched_feat(UTIL_EST))
+ return;
+
+ /* Avoid store if the flag has been already set */
+ enqueued = avg->util_est.enqueued;
+ if (!(enqueued & UTIL_AVG_UNCHANGED))
+ return;
+
+ /* Reset flag to report util_avg has been updated */
+ enqueued &= ~UTIL_AVG_UNCHANGED;
+ WRITE_ONCE(avg->util_est.enqueued, enqueued);
+}
+
/*
* sched_entity:
*
cfs_rq->curr == se)) {
___update_load_avg(&se->avg, se_weight(se), se_runnable(se));
+ cfs_se_util_change(&se->avg);
return 1;
}
}
/*
- * Called within set_task_rq() right before setting a task's cpu. The
+ * Called within set_task_rq() right before setting a task's CPU. The
* caller only guarantees p->pi_lock is held; no other assumptions,
* including the state of rq->lock, should be made.
*/
/*
* runnable_sum can't be lower than running_sum
- * As running sum is scale with cpu capacity wehreas the runnable sum
+ * As running sum is scale with CPU capacity wehreas the runnable sum
* is not we rescale running_sum 1st
*/
running_sum = se->avg.util_sum /
#endif
if (decayed)
- cfs_rq_util_change(cfs_rq);
+ cfs_rq_util_change(cfs_rq, 0);
return decayed;
}
* Must call update_cfs_rq_load_avg() before this, since we rely on
* cfs_rq->avg.last_update_time being current.
*/
-static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
+static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
{
u32 divider = LOAD_AVG_MAX - 1024 + cfs_rq->avg.period_contrib;
add_tg_cfs_propagate(cfs_rq, se->avg.load_sum);
- cfs_rq_util_change(cfs_rq);
+ cfs_rq_util_change(cfs_rq, flags);
}
/**
add_tg_cfs_propagate(cfs_rq, -se->avg.load_sum);
- cfs_rq_util_change(cfs_rq);
+ cfs_rq_util_change(cfs_rq, 0);
}
/*
if (!se->avg.last_update_time && (flags & DO_ATTACH)) {
- attach_entity_load_avg(cfs_rq, se);
+ /*
+ * DO_ATTACH means we're here from enqueue_entity().
+ * !last_update_time means we've passed through
+ * migrate_task_rq_fair() indicating we migrated.
+ *
+ * IOW we're enqueueing a task on a new CPU.
+ */
+ attach_entity_load_avg(cfs_rq, se, SCHED_CPUFREQ_MIGRATION);
update_tg_load_avg(cfs_rq, 0);
} else if (decayed && (flags & UPDATE_TG))
static int idle_balance(struct rq *this_rq, struct rq_flags *rf);
+static inline unsigned long task_util(struct task_struct *p)
+{
+ return READ_ONCE(p->se.avg.util_avg);
+}
+
+static inline unsigned long _task_util_est(struct task_struct *p)
+{
+ struct util_est ue = READ_ONCE(p->se.avg.util_est);
+
+ return max(ue.ewma, ue.enqueued);
+}
+
+static inline unsigned long task_util_est(struct task_struct *p)
+{
+ return max(task_util(p), _task_util_est(p));
+}
+
+static inline void util_est_enqueue(struct cfs_rq *cfs_rq,
+ struct task_struct *p)
+{
+ unsigned int enqueued;
+
+ if (!sched_feat(UTIL_EST))
+ return;
+
+ /* Update root cfs_rq's estimated utilization */
+ enqueued = cfs_rq->avg.util_est.enqueued;
+ enqueued += (_task_util_est(p) | UTIL_AVG_UNCHANGED);
+ WRITE_ONCE(cfs_rq->avg.util_est.enqueued, enqueued);
+}
+
+/*
+ * Check if a (signed) value is within a specified (unsigned) margin,
+ * based on the observation that:
+ *
+ * abs(x) < y := (unsigned)(x + y - 1) < (2 * y - 1)
+ *
+ * NOTE: this only works when value + maring < INT_MAX.
+ */
+static inline bool within_margin(int value, int margin)
+{
+ return ((unsigned int)(value + margin - 1) < (2 * margin - 1));
+}
+
+static void
+util_est_dequeue(struct cfs_rq *cfs_rq, struct task_struct *p, bool task_sleep)
+{
+ long last_ewma_diff;
+ struct util_est ue;
+
+ if (!sched_feat(UTIL_EST))
+ return;
+
+ /*
+ * Update root cfs_rq's estimated utilization
+ *
+ * If *p is the last task then the root cfs_rq's estimated utilization
+ * of a CPU is 0 by definition.
+ */
+ ue.enqueued = 0;
+ if (cfs_rq->nr_running) {
+ ue.enqueued = cfs_rq->avg.util_est.enqueued;
+ ue.enqueued -= min_t(unsigned int, ue.enqueued,
+ (_task_util_est(p) | UTIL_AVG_UNCHANGED));
+ }
+ WRITE_ONCE(cfs_rq->avg.util_est.enqueued, ue.enqueued);
+
+ /*
+ * Skip update of task's estimated utilization when the task has not
+ * yet completed an activation, e.g. being migrated.
+ */
+ if (!task_sleep)
+ return;
+
+ /*
+ * If the PELT values haven't changed since enqueue time,
+ * skip the util_est update.
+ */
+ ue = p->se.avg.util_est;
+ if (ue.enqueued & UTIL_AVG_UNCHANGED)
+ return;
+
+ /*
+ * Skip update of task's estimated utilization when its EWMA is
+ * already ~1% close to its last activation value.
+ */
+ ue.enqueued = (task_util(p) | UTIL_AVG_UNCHANGED);
+ last_ewma_diff = ue.enqueued - ue.ewma;
+ if (within_margin(last_ewma_diff, (SCHED_CAPACITY_SCALE / 100)))
+ return;
+
+ /*
+ * Update Task's estimated utilization
+ *
+ * When *p completes an activation we can consolidate another sample
+ * of the task size. This is done by storing the current PELT value
+ * as ue.enqueued and by using this value to update the Exponential
+ * Weighted Moving Average (EWMA):
+ *
+ * ewma(t) = w * task_util(p) + (1-w) * ewma(t-1)
+ * = w * task_util(p) + ewma(t-1) - w * ewma(t-1)
+ * = w * (task_util(p) - ewma(t-1)) + ewma(t-1)
+ * = w * ( last_ewma_diff ) + ewma(t-1)
+ * = w * (last_ewma_diff + ewma(t-1) / w)
+ *
+ * Where 'w' is the weight of new samples, which is configured to be
+ * 0.25, thus making w=1/4 ( >>= UTIL_EST_WEIGHT_SHIFT)
+ */
+ ue.ewma <<= UTIL_EST_WEIGHT_SHIFT;
+ ue.ewma += last_ewma_diff;
+ ue.ewma >>= UTIL_EST_WEIGHT_SHIFT;
+ WRITE_ONCE(p->se.avg.util_est, ue);
+}
+
#else /* CONFIG_SMP */
static inline int
static inline void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int not_used1)
{
- cfs_rq_util_change(cfs_rq);
+ cfs_rq_util_change(cfs_rq, 0);
}
static inline void remove_entity_load_avg(struct sched_entity *se) {}
static inline void
-attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
+attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) {}
static inline void
detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
return 0;
}
+static inline void
+util_est_enqueue(struct cfs_rq *cfs_rq, struct task_struct *p) {}
+
+static inline void
+util_est_dequeue(struct cfs_rq *cfs_rq, struct task_struct *p,
+ bool task_sleep) {}
+
#endif /* CONFIG_SMP */
static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se)
if (!se)
add_nr_running(rq, task_delta);
- /* determine whether we need to wake up potentially idle cpu */
+ /* Determine whether we need to wake up potentially idle CPU: */
if (rq->curr == rq->idle && rq->cfs.nr_running)
resched_curr(rq);
}
}
/*
- * Both these cpu hotplug callbacks race against unregister_fair_sched_group()
+ * Both these CPU hotplug callbacks race against unregister_fair_sched_group()
*
* The race is harmless, since modifying bandwidth settings of unhooked group
* bits doesn't do much.
*/
cfs_rq->runtime_remaining = 1;
/*
- * Offline rq is schedulable till cpu is completely disabled
+ * Offline rq is schedulable till CPU is completely disabled
* in take_cpu_down(), so we prevent new cfs throttling here.
*/
cfs_rq->runtime_enabled = 0;
if (!se)
add_nr_running(rq, 1);
+ util_est_enqueue(&rq->cfs, p);
hrtick_update(rq);
}
if (!se)
sub_nr_running(rq, 1);
+ util_est_dequeue(&rq->cfs, p, task_sleep);
hrtick_update(rq);
}
*
* load' = (1 - 1/2^i) * load + (1/2^i) * cur_load
*
- * If a cpu misses updates for n ticks (as it was idle) and update gets
- * called on the n+1-th tick when cpu may be busy, then we have:
+ * If a CPU misses updates for n ticks (as it was idle) and update gets
+ * called on the n+1-th tick when CPU may be busy, then we have:
*
* load_n = (1 - 1/2^i)^n * load_0
* load_n+1 = (1 - 1/2^i) * load_n + (1/2^i) * cur_load
}
return load;
}
+
+static struct {
+ cpumask_var_t idle_cpus_mask;
+ atomic_t nr_cpus;
+ int has_blocked; /* Idle CPUS has blocked load */
+ unsigned long next_balance; /* in jiffy units */
+ unsigned long next_blocked; /* Next update of blocked load in jiffies */
+} nohz ____cacheline_aligned;
+
#endif /* CONFIG_NO_HZ_COMMON */
/**
#ifdef CONFIG_NO_HZ_COMMON
/*
* There is no sane way to deal with nohz on smp when using jiffies because the
- * cpu doing the jiffies update might drift wrt the cpu doing the jiffy reading
+ * CPU doing the jiffies update might drift wrt the CPU doing the jiffy reading
* causing off-by-one errors in observed deltas; {0,2} instead of {1,1}.
*
* Therefore we need to avoid the delta approach from the regular tick when
}
/*
- * Return a low guess at the load of a migration-source cpu weighted
+ * Return a low guess at the load of a migration-source CPU weighted
* according to the scheduling class and "nice" value.
*
* We want to under-estimate the load of migration sources, to
}
/*
- * Return a high guess at the load of a migration-target cpu weighted
+ * Return a high guess at the load of a migration-target CPU weighted
* according to the scheduling class and "nice" value.
*/
static unsigned long target_load(int cpu, int type)
unsigned long task_load;
this_eff_load = target_load(this_cpu, sd->wake_idx);
- prev_eff_load = source_load(prev_cpu, sd->wake_idx);
if (sync) {
unsigned long current_load = task_h_load(current);
this_eff_load *= 100;
this_eff_load *= capacity_of(prev_cpu);
+ prev_eff_load = source_load(prev_cpu, sd->wake_idx);
prev_eff_load -= task_load;
if (sched_feat(WA_BIAS))
prev_eff_load *= 100 + (sd->imbalance_pct - 100) / 2;
prev_eff_load *= capacity_of(this_cpu);
- return this_eff_load <= prev_eff_load ? this_cpu : nr_cpumask_bits;
+ /*
+ * If sync, adjust the weight of prev_eff_load such that if
+ * prev_eff == this_eff that select_idle_sibling() will consider
+ * stacking the wakee on top of the waker if no other CPU is
+ * idle.
+ */
+ if (sync)
+ prev_eff_load += 1;
+
+ return this_eff_load < prev_eff_load ? this_cpu : nr_cpumask_bits;
+}
+
+#ifdef CONFIG_NUMA_BALANCING
+static void
+update_wa_numa_placement(struct task_struct *p, int prev_cpu, int target)
+{
+ unsigned long interval;
+
+ if (!static_branch_likely(&sched_numa_balancing))
+ return;
+
+ /* If balancing has no preference then continue gathering data */
+ if (p->numa_preferred_nid == -1)
+ return;
+
+ /*
+ * If the wakeup is not affecting locality then it is neutral from
+ * the perspective of NUMA balacing so continue gathering data.
+ */
+ if (cpu_to_node(prev_cpu) == cpu_to_node(target))
+ return;
+
+ /*
+ * Temporarily prevent NUMA balancing trying to place waker/wakee after
+ * wakee has been moved by wake_affine. This will potentially allow
+ * related tasks to converge and update their data placement. The
+ * 4 * numa_scan_period is to allow the two-pass filter to migrate
+ * hot data to the wakers node.
+ */
+ interval = max(sysctl_numa_balancing_scan_delay,
+ p->numa_scan_period << 2);
+ p->numa_migrate_retry = jiffies + msecs_to_jiffies(interval);
+
+ interval = max(sysctl_numa_balancing_scan_delay,
+ current->numa_scan_period << 2);
+ current->numa_migrate_retry = jiffies + msecs_to_jiffies(interval);
+}
+#else
+static void
+update_wa_numa_placement(struct task_struct *p, int prev_cpu, int target)
+{
}
+#endif
static int wake_affine(struct sched_domain *sd, struct task_struct *p,
- int prev_cpu, int sync)
+ int this_cpu, int prev_cpu, int sync)
{
- int this_cpu = smp_processor_id();
int target = nr_cpumask_bits;
if (sched_feat(WA_IDLE))
if (target == nr_cpumask_bits)
return prev_cpu;
+ update_wa_numa_placement(p, prev_cpu, target);
schedstat_inc(sd->ttwu_move_affine);
schedstat_inc(p->se.statistics.nr_wakeups_affine);
return target;
}
-static inline unsigned long task_util(struct task_struct *p);
static unsigned long cpu_util_wake(int cpu, struct task_struct *p);
static unsigned long capacity_spare_wake(int cpu, struct task_struct *p)
max_spare_cap = 0;
for_each_cpu(i, sched_group_span(group)) {
- /* Bias balancing toward cpus of our domain */
+ /* Bias balancing toward CPUs of our domain */
if (local_group)
load = source_load(i, load_idx);
else
if (min_runnable_load > (runnable_load + imbalance)) {
/*
* The runnable load is significantly smaller
- * so we can pick this new cpu
+ * so we can pick this new CPU:
*/
min_runnable_load = runnable_load;
min_avg_load = avg_load;
(100*min_avg_load > imbalance_scale*avg_load)) {
/*
* The runnable loads are close so take the
- * blocked load into account through avg_load.
+ * blocked load into account through avg_load:
*/
min_avg_load = avg_load;
idlest = group;
if (!idlest)
return NULL;
+ /*
+ * When comparing groups across NUMA domains, it's possible for the
+ * local domain to be very lightly loaded relative to the remote
+ * domains but "imbalance" skews the comparison making remote CPUs
+ * look much more favourable. When considering cross-domain, add
+ * imbalance to the runnable load on the remote node and consider
+ * staying local.
+ */
+ if ((sd->flags & SD_NUMA) &&
+ min_runnable_load + imbalance >= this_runnable_load)
+ return NULL;
+
if (min_runnable_load > (this_runnable_load + imbalance))
return NULL;
}
/*
- * find_idlest_group_cpu - find the idlest cpu among the cpus in group.
+ * find_idlest_group_cpu - find the idlest CPU among the CPUs in the group.
*/
static int
find_idlest_group_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
new_cpu = find_idlest_group_cpu(group, p, cpu);
if (new_cpu == cpu) {
- /* Now try balancing at a lower domain level of cpu */
+ /* Now try balancing at a lower domain level of 'cpu': */
sd = sd->child;
continue;
}
- /* Now try balancing at a lower domain level of new_cpu */
+ /* Now try balancing at a lower domain level of 'new_cpu': */
cpu = new_cpu;
weight = sd->span_weight;
sd = NULL;
if (tmp->flags & sd_flag)
sd = tmp;
}
- /* while loop will break here if sd == NULL */
}
return new_cpu;
return target;
/*
- * If the previous cpu is cache affine and idle, don't be stupid.
+ * If the previous CPU is cache affine and idle, don't be stupid:
*/
if (prev != target && cpus_share_cache(prev, target) && idle_cpu(prev))
return prev;
- /* Check a recently used CPU as a potential idle candidate */
+ /* Check a recently used CPU as a potential idle candidate: */
recent_used_cpu = p->recent_used_cpu;
if (recent_used_cpu != prev &&
recent_used_cpu != target &&
cpumask_test_cpu(p->recent_used_cpu, &p->cpus_allowed)) {
/*
* Replace recent_used_cpu with prev as it is a potential
- * candidate for the next wake.
+ * candidate for the next wake:
*/
p->recent_used_cpu = prev;
return recent_used_cpu;
return target;
}
-/*
- * cpu_util returns the amount of capacity of a CPU that is used by CFS
- * tasks. The unit of the return value must be the one of capacity so we can
- * compare the utilization with the capacity of the CPU that is available for
- * CFS task (ie cpu_capacity).
+/**
+ * Amount of capacity of a CPU that is (estimated to be) used by CFS tasks
+ * @cpu: the CPU to get the utilization of
+ *
+ * The unit of the return value must be the one of capacity so we can compare
+ * the utilization with the capacity of the CPU that is available for CFS task
+ * (ie cpu_capacity).
*
* cfs_rq.avg.util_avg is the sum of running time of runnable tasks plus the
* recent utilization of currently non-runnable tasks on a CPU. It represents
* current capacity (capacity_curr <= capacity_orig) of the CPU because it is
* the running time on this CPU scaled by capacity_curr.
*
+ * The estimated utilization of a CPU is defined to be the maximum between its
+ * cfs_rq.avg.util_avg and the sum of the estimated utilization of the tasks
+ * currently RUNNABLE on that CPU.
+ * This allows to properly represent the expected utilization of a CPU which
+ * has just got a big task running since a long sleep period. At the same time
+ * however it preserves the benefits of the "blocked utilization" in
+ * describing the potential for other tasks waking up on the same CPU.
+ *
* Nevertheless, cfs_rq.avg.util_avg can be higher than capacity_curr or even
* higher than capacity_orig because of unfortunate rounding in
* cfs.avg.util_avg or just after migrating tasks and new task wakeups until
* available capacity. We allow utilization to overshoot capacity_curr (but not
* capacity_orig) as it useful for predicting the capacity required after task
* migrations (scheduler-driven DVFS).
+ *
+ * Return: the (estimated) utilization for the specified CPU
*/
-static unsigned long cpu_util(int cpu)
+static inline unsigned long cpu_util(int cpu)
{
- unsigned long util = cpu_rq(cpu)->cfs.avg.util_avg;
- unsigned long capacity = capacity_orig_of(cpu);
+ struct cfs_rq *cfs_rq;
+ unsigned int util;
- return (util >= capacity) ? capacity : util;
-}
+ cfs_rq = &cpu_rq(cpu)->cfs;
+ util = READ_ONCE(cfs_rq->avg.util_avg);
-static inline unsigned long task_util(struct task_struct *p)
-{
- return p->se.avg.util_avg;
+ if (sched_feat(UTIL_EST))
+ util = max(util, READ_ONCE(cfs_rq->avg.util_est.enqueued));
+
+ return min_t(unsigned long, util, capacity_orig_of(cpu));
}
/*
- * cpu_util_wake: Compute cpu utilization with any contributions from
+ * cpu_util_wake: Compute CPU utilization with any contributions from
* the waking task p removed.
*/
static unsigned long cpu_util_wake(int cpu, struct task_struct *p)
{
- unsigned long util, capacity;
+ struct cfs_rq *cfs_rq;
+ unsigned int util;
/* Task has no contribution or is new */
- if (cpu != task_cpu(p) || !p->se.avg.last_update_time)
+ if (cpu != task_cpu(p) || !READ_ONCE(p->se.avg.last_update_time))
return cpu_util(cpu);
- capacity = capacity_orig_of(cpu);
- util = max_t(long, cpu_rq(cpu)->cfs.avg.util_avg - task_util(p), 0);
+ cfs_rq = &cpu_rq(cpu)->cfs;
+ util = READ_ONCE(cfs_rq->avg.util_avg);
+
+ /* Discount task's blocked util from CPU's util */
+ util -= min_t(unsigned int, util, task_util(p));
+
+ /*
+ * Covered cases:
+ *
+ * a) if *p is the only task sleeping on this CPU, then:
+ * cpu_util (== task_util) > util_est (== 0)
+ * and thus we return:
+ * cpu_util_wake = (cpu_util - task_util) = 0
+ *
+ * b) if other tasks are SLEEPING on this CPU, which is now exiting
+ * IDLE, then:
+ * cpu_util >= task_util
+ * cpu_util > util_est (== 0)
+ * and thus we discount *p's blocked utilization to return:
+ * cpu_util_wake = (cpu_util - task_util) >= 0
+ *
+ * c) if other tasks are RUNNABLE on that CPU and
+ * util_est > cpu_util
+ * then we use util_est since it returns a more restrictive
+ * estimation of the spare capacity on that CPU, by just
+ * considering the expected utilization of tasks already
+ * runnable on that CPU.
+ *
+ * Cases a) and b) are covered by the above code, while case c) is
+ * covered by the following code when estimated utilization is
+ * enabled.
+ */
+ if (sched_feat(UTIL_EST))
+ util = max(util, READ_ONCE(cfs_rq->avg.util_est.enqueued));
- return (util >= capacity) ? capacity : util;
+ /*
+ * Utilization (estimated) can exceed the CPU capacity, thus let's
+ * clamp to the maximum CPU capacity to ensure consistency with
+ * the cpu_util call.
+ */
+ return min_t(unsigned long, util, capacity_orig_of(cpu));
}
/*
* that have the 'sd_flag' flag set. In practice, this is SD_BALANCE_WAKE,
* SD_BALANCE_FORK, or SD_BALANCE_EXEC.
*
- * Balances load by selecting the idlest cpu in the idlest group, or under
- * certain conditions an idle sibling cpu if the domain has SD_WAKE_AFFINE set.
+ * Balances load by selecting the idlest CPU in the idlest group, or under
+ * certain conditions an idle sibling CPU if the domain has SD_WAKE_AFFINE set.
*
- * Returns the target cpu number.
+ * Returns the target CPU number.
*
* preempt must be disabled.
*/
int cpu = smp_processor_id();
int new_cpu = prev_cpu;
int want_affine = 0;
- int sync = wake_flags & WF_SYNC;
+ int sync = (wake_flags & WF_SYNC) && !(current->flags & PF_EXITING);
if (sd_flag & SD_BALANCE_WAKE) {
record_wakee(p);
break;
/*
- * If both cpu and prev_cpu are part of this domain,
+ * If both 'cpu' and 'prev_cpu' are part of this domain,
* cpu is a valid SD_WAKE_AFFINE target.
*/
if (want_affine && (tmp->flags & SD_WAKE_AFFINE) &&
if (cpu == prev_cpu)
goto pick_cpu;
- new_cpu = wake_affine(affine_sd, p, prev_cpu, sync);
+ new_cpu = wake_affine(affine_sd, p, cpu, prev_cpu, sync);
}
if (sd && !(sd_flag & SD_BALANCE_FORK)) {
static void detach_entity_cfs_rq(struct sched_entity *se);
/*
- * Called immediately before a task is migrated to a new cpu; task_cpu(p) and
+ * Called immediately before a task is migrated to a new CPU; task_cpu(p) and
* cfs_rq_of(p) references at time of call are still valid and identify the
- * previous cpu. The caller guarantees p->pi_lock or task_rq(p)->lock is held.
+ * previous CPU. The caller guarantees p->pi_lock or task_rq(p)->lock is held.
*/
static void migrate_task_rq_fair(struct task_struct *p)
{
p = task_of(se);
-done: __maybe_unused
+done: __maybe_unused;
#ifdef CONFIG_SMP
/*
* Move the next running task to the front of
* BASICS
*
* The purpose of load-balancing is to achieve the same basic fairness the
- * per-cpu scheduler provides, namely provide a proportional amount of compute
+ * per-CPU scheduler provides, namely provide a proportional amount of compute
* time to each task. This is expressed in the following equation:
*
* W_i,n/P_i == W_j,n/P_j for all i,j (1)
*
- * Where W_i,n is the n-th weight average for cpu i. The instantaneous weight
+ * Where W_i,n is the n-th weight average for CPU i. The instantaneous weight
* W_i,0 is defined as:
*
* W_i,0 = \Sum_j w_i,j (2)
*
- * Where w_i,j is the weight of the j-th runnable task on cpu i. This weight
+ * Where w_i,j is the weight of the j-th runnable task on CPU i. This weight
* is derived from the nice value as per sched_prio_to_weight[].
*
* The weight average is an exponential decay average of the instantaneous
*
* W'_i,n = (2^n - 1) / 2^n * W_i,n + 1 / 2^n * W_i,0 (3)
*
- * C_i is the compute capacity of cpu i, typically it is the
+ * C_i is the compute capacity of CPU i, typically it is the
* fraction of 'recent' time available for SCHED_OTHER task execution. But it
* can also include other factors [XXX].
*
* SCHED DOMAINS
*
* In order to solve the imbalance equation (4), and avoid the obvious O(n^2)
- * for all i,j solution, we create a tree of cpus that follows the hardware
+ * for all i,j solution, we create a tree of CPUs that follows the hardware
* topology where each level pairs two lower groups (or better). This results
- * in O(log n) layers. Furthermore we reduce the number of cpus going up the
+ * in O(log n) layers. Furthermore we reduce the number of CPUs going up the
* tree to only the first of the previous level and we decrease the frequency
- * of load-balance at each level inv. proportional to the number of cpus in
+ * of load-balance at each level inv. proportional to the number of CPUs in
* the groups.
*
* This yields:
* \Sum { --- * --- * 2^i } = O(n) (5)
* i = 0 2^i 2^i
* `- size of each group
- * | | `- number of cpus doing load-balance
+ * | | `- number of CPUs doing load-balance
* | `- freq
* `- sum over all levels
*
* this makes (5) the runtime complexity of the balancer.
*
* An important property here is that each CPU is still (indirectly) connected
- * to every other cpu in at most O(log n) steps:
+ * to every other CPU in at most O(log n) steps:
*
* The adjacency matrix of the resulting graph is given by:
*
*
* A^(log_2 n)_i,j != 0 for all i,j (7)
*
- * Showing there's indeed a path between every cpu in at most O(log n) steps.
+ * Showing there's indeed a path between every CPU in at most O(log n) steps.
* The task movement gives a factor of O(m), giving a convergence complexity
* of:
*
* WORK CONSERVING
*
* In order to avoid CPUs going idle while there's still work to do, new idle
- * balancing is more aggressive and has the newly idle cpu iterate up the domain
+ * balancing is more aggressive and has the newly idle CPU iterate up the domain
* tree itself instead of relying on other CPUs to bring it work.
*
* This adds some complexity to both (5) and (8) but it reduces the total idle
*
* s_k,i = \Sum_j w_i,j,k and S_k = \Sum_i s_k,i (10)
*
- * w_i,j,k is the weight of the j-th runnable task in the k-th cgroup on cpu i.
+ * w_i,j,k is the weight of the j-th runnable task in the k-th cgroup on CPU i.
*
* The big problem is S_k, its a global sum needed to compute a local (W_i)
* property.
#define LBF_NEED_BREAK 0x02
#define LBF_DST_PINNED 0x04
#define LBF_SOME_PINNED 0x08
+#define LBF_NOHZ_STATS 0x10
+#define LBF_NOHZ_AGAIN 0x20
struct lb_env {
struct sched_domain *sd;
env->flags |= LBF_SOME_PINNED;
/*
- * Remember if this task can be migrated to any other cpu in
+ * Remember if this task can be migrated to any other CPU in
* our sched_group. We may want to revisit it if we couldn't
* meet load balance goals by pulling other tasks on src_cpu.
*
if (env->idle == CPU_NEWLY_IDLE || (env->flags & LBF_DST_PINNED))
return 0;
- /* Prevent to re-select dst_cpu via env's cpus */
+ /* Prevent to re-select dst_cpu via env's CPUs: */
for_each_cpu_and(cpu, env->dst_grpmask, env->cpus) {
if (cpumask_test_cpu(cpu, &p->cpus_allowed)) {
env->flags |= LBF_DST_PINNED;
rq_unlock(env->dst_rq, &rf);
}
+static inline bool cfs_rq_has_blocked(struct cfs_rq *cfs_rq)
+{
+ if (cfs_rq->avg.load_avg)
+ return true;
+
+ if (cfs_rq->avg.util_avg)
+ return true;
+
+ return false;
+}
+
#ifdef CONFIG_FAIR_GROUP_SCHED
static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
struct rq *rq = cpu_rq(cpu);
struct cfs_rq *cfs_rq, *pos;
struct rq_flags rf;
+ bool done = true;
rq_lock_irqsave(rq, &rf);
update_rq_clock(rq);
*/
if (cfs_rq_is_decayed(cfs_rq))
list_del_leaf_cfs_rq(cfs_rq);
+
+ /* Don't need periodic decay once load/util_avg are null */
+ if (cfs_rq_has_blocked(cfs_rq))
+ done = false;
}
+
+#ifdef CONFIG_NO_HZ_COMMON
+ rq->last_blocked_load_update_tick = jiffies;
+ if (done)
+ rq->has_blocked_load = 0;
+#endif
rq_unlock_irqrestore(rq, &rf);
}
rq_lock_irqsave(rq, &rf);
update_rq_clock(rq);
update_cfs_rq_load_avg(cfs_rq_clock_task(cfs_rq), cfs_rq);
+#ifdef CONFIG_NO_HZ_COMMON
+ rq->last_blocked_load_update_tick = jiffies;
+ if (!cfs_rq_has_blocked(cfs_rq))
+ rq->has_blocked_load = 0;
+#endif
rq_unlock_irqrestore(rq, &rf);
}
* Group imbalance indicates (and tries to solve) the problem where balancing
* groups is inadequate due to ->cpus_allowed constraints.
*
- * Imagine a situation of two groups of 4 cpus each and 4 tasks each with a
- * cpumask covering 1 cpu of the first group and 3 cpus of the second group.
+ * Imagine a situation of two groups of 4 CPUs each and 4 tasks each with a
+ * cpumask covering 1 CPU of the first group and 3 CPUs of the second group.
* Something like:
*
* { 0 1 2 3 } { 4 5 6 7 }
*
* If we were to balance group-wise we'd place two tasks in the first group and
* two tasks in the second group. Clearly this is undesired as it will overload
- * cpu 3 and leave one of the cpus in the second group unused.
+ * cpu 3 and leave one of the CPUs in the second group unused.
*
* The current solution to this issue is detecting the skew in the first group
* by noticing the lower domain failed to reach balance and had difficulty
return group_other;
}
+static bool update_nohz_stats(struct rq *rq, bool force)
+{
+#ifdef CONFIG_NO_HZ_COMMON
+ unsigned int cpu = rq->cpu;
+
+ if (!rq->has_blocked_load)
+ return false;
+
+ if (!cpumask_test_cpu(cpu, nohz.idle_cpus_mask))
+ return false;
+
+ if (!force && !time_after(jiffies, rq->last_blocked_load_update_tick))
+ return true;
+
+ update_blocked_averages(cpu);
+
+ return rq->has_blocked_load;
+#else
+ return false;
+#endif
+}
+
/**
* update_sg_lb_stats - Update sched_group's statistics for load balancing.
* @env: The load balancing environment.
for_each_cpu_and(i, sched_group_span(group), env->cpus) {
struct rq *rq = cpu_rq(i);
- /* Bias balancing toward cpus of our domain */
+ if ((env->flags & LBF_NOHZ_STATS) && update_nohz_stats(rq, false))
+ env->flags |= LBF_NOHZ_AGAIN;
+
+ /* Bias balancing toward CPUs of our domain: */
if (local_group)
load = target_load(i, load_idx);
else
if (!(env->sd->flags & SD_ASYM_PACKING))
return true;
- /* No ASYM_PACKING if target cpu is already busy */
+ /* No ASYM_PACKING if target CPU is already busy */
if (env->idle == CPU_NOT_IDLE)
return true;
/*
if (!sds->busiest)
return true;
- /* Prefer to move from lowest priority cpu's work */
+ /* Prefer to move from lowest priority CPU's work */
if (sched_asym_prefer(sds->busiest->asym_prefer_cpu,
sg->asym_prefer_cpu))
return true;
if (child && child->flags & SD_PREFER_SIBLING)
prefer_sibling = 1;
+#ifdef CONFIG_NO_HZ_COMMON
+ if (env->idle == CPU_NEWLY_IDLE && READ_ONCE(nohz.has_blocked))
+ env->flags |= LBF_NOHZ_STATS;
+#endif
+
load_idx = get_sd_load_idx(env->sd, env->idle);
do {
sg = sg->next;
} while (sg != env->sd->groups);
+#ifdef CONFIG_NO_HZ_COMMON
+ if ((env->flags & LBF_NOHZ_AGAIN) &&
+ cpumask_subset(nohz.idle_cpus_mask, sched_domain_span(env->sd))) {
+
+ WRITE_ONCE(nohz.next_blocked,
+ jiffies + msecs_to_jiffies(LOAD_AVG_PERIOD));
+ }
+#endif
+
if (env->sd->flags & SD_NUMA)
env->fbq_type = fbq_classify_group(&sds->busiest_stat);
if (busiest->group_type == group_imbalanced) {
/*
* In the group_imb case we cannot rely on group-wide averages
- * to ensure cpu-load equilibrium, look at wider averages. XXX
+ * to ensure CPU-load equilibrium, look at wider averages. XXX
*/
busiest->load_per_task =
min(busiest->load_per_task, sds->avg_load);
}
/*
- * If there aren't any idle cpus, avoid creating some.
+ * If there aren't any idle CPUs, avoid creating some.
*/
if (busiest->group_type == group_overloaded &&
local->group_type == group_overloaded) {
}
/*
- * We're trying to get all the cpus to the average_load, so we don't
+ * We're trying to get all the CPUs to the average_load, so we don't
* want to push ourselves above the average load, nor do we wish to
- * reduce the max loaded cpu below the average load. At the same time,
+ * reduce the max loaded CPU below the average load. At the same time,
* we also don't want to reduce the group load below the group
* capacity. Thus we look for the minimum possible imbalance.
*/
if (env->idle == CPU_IDLE) {
/*
- * This cpu is idle. If the busiest group is not overloaded
+ * This CPU is idle. If the busiest group is not overloaded
* and there is no imbalance between this and busiest group
- * wrt idle cpus, it is balanced. The imbalance becomes
+ * wrt idle CPUs, it is balanced. The imbalance becomes
* significant if the diff is greater than 1 otherwise we
* might end up to just move the imbalance on another group
*/
}
/*
- * find_busiest_queue - find the busiest runqueue among the cpus in group.
+ * find_busiest_queue - find the busiest runqueue among the CPUs in the group.
*/
static struct rq *find_busiest_queue(struct lb_env *env,
struct sched_group *group)
/*
* When comparing with imbalance, use weighted_cpuload()
- * which is not scaled with the cpu capacity.
+ * which is not scaled with the CPU capacity.
*/
if (rq->nr_running == 1 && wl > env->imbalance &&
continue;
/*
- * For the load comparisons with the other cpu's, consider
- * the weighted_cpuload() scaled with the cpu capacity, so
- * that the load can be moved away from the cpu that is
+ * For the load comparisons with the other CPU's, consider
+ * the weighted_cpuload() scaled with the CPU capacity, so
+ * that the load can be moved away from the CPU that is
* potentially running at a lower capacity.
*
* Thus we're looking for max(wl_i / capacity_i), crosswise
return 0;
/*
- * In the newly idle case, we will allow all the cpu's
+ * In the newly idle case, we will allow all the CPUs
* to do the newly idle load balance.
*/
if (env->idle == CPU_NEWLY_IDLE)
return 1;
- /* Try to find first idle cpu */
+ /* Try to find first idle CPU */
for_each_cpu_and(cpu, group_balance_mask(sg), env->cpus) {
if (!idle_cpu(cpu))
continue;
balance_cpu = group_balance_cpu(sg);
/*
- * First idle cpu or the first cpu(busiest) in this sched group
+ * First idle CPU or the first CPU(busiest) in this sched group
* is eligible for doing load balancing at this and above domains.
*/
return balance_cpu == env->dst_cpu;
* Revisit (affine) tasks on src_cpu that couldn't be moved to
* us and move them to an alternate dst_cpu in our sched_group
* where they can run. The upper limit on how many times we
- * iterate on same src_cpu is dependent on number of cpus in our
+ * iterate on same src_cpu is dependent on number of CPUs in our
* sched_group.
*
* This changes load balance semantics a bit on who can move
*/
if ((env.flags & LBF_DST_PINNED) && env.imbalance > 0) {
- /* Prevent to re-select dst_cpu via env's cpus */
+ /* Prevent to re-select dst_cpu via env's CPUs */
cpumask_clear_cpu(env.dst_cpu, env.cpus);
env.dst_rq = cpu_rq(env.new_dst_cpu);
raw_spin_lock_irqsave(&busiest->lock, flags);
- /* don't kick the active_load_balance_cpu_stop,
- * if the curr task on busiest cpu can't be
- * moved to this_cpu
+ /*
+ * Don't kick the active_load_balance_cpu_stop,
+ * if the curr task on busiest CPU can't be
+ * moved to this_cpu:
*/
if (!cpumask_test_cpu(this_cpu, &busiest->curr->cpus_allowed)) {
raw_spin_unlock_irqrestore(&busiest->lock,
}
/*
- * idle_balance is called by schedule() if this_cpu is about to become
- * idle. Attempts to pull tasks from other CPUs.
+ * active_load_balance_cpu_stop is run by the CPU stopper. It pushes
+ * running tasks off the busiest CPU onto idle CPUs. It requires at
+ * least 1 task to be running on each physical CPU where possible, and
+ * avoids physical / logical imbalances.
*/
-static int idle_balance(struct rq *this_rq, struct rq_flags *rf)
+static int active_load_balance_cpu_stop(void *data)
{
- unsigned long next_balance = jiffies + HZ;
- int this_cpu = this_rq->cpu;
+ struct rq *busiest_rq = data;
+ int busiest_cpu = cpu_of(busiest_rq);
+ int target_cpu = busiest_rq->push_cpu;
+ struct rq *target_rq = cpu_rq(target_cpu);
struct sched_domain *sd;
- int pulled_task = 0;
- u64 curr_cost = 0;
+ struct task_struct *p = NULL;
+ struct rq_flags rf;
+ rq_lock_irq(busiest_rq, &rf);
/*
- * We must set idle_stamp _before_ calling idle_balance(), such that we
- * measure the duration of idle_balance() as idle time.
+ * Between queueing the stop-work and running it is a hole in which
+ * CPUs can become inactive. We should not move tasks from or to
+ * inactive CPUs.
*/
- this_rq->idle_stamp = rq_clock(this_rq);
+ if (!cpu_active(busiest_cpu) || !cpu_active(target_cpu))
+ goto out_unlock;
- /*
- * Do not pull tasks towards !active CPUs...
- */
- if (!cpu_active(this_cpu))
- return 0;
+ /* Make sure the requested CPU hasn't gone down in the meantime: */
+ if (unlikely(busiest_cpu != smp_processor_id() ||
+ !busiest_rq->active_balance))
+ goto out_unlock;
+
+ /* Is there any task to move? */
+ if (busiest_rq->nr_running <= 1)
+ goto out_unlock;
/*
- * This is OK, because current is on_cpu, which avoids it being picked
- * for load-balance and preemption/IRQs are still disabled avoiding
- * further scheduler activity on it and we're being very careful to
- * re-start the picking loop.
+ * This condition is "impossible", if it occurs
+ * we need to fix it. Originally reported by
+ * Bjorn Helgaas on a 128-CPU setup.
*/
- rq_unpin_lock(this_rq, rf);
-
- if (this_rq->avg_idle < sysctl_sched_migration_cost ||
- !this_rq->rd->overload) {
- rcu_read_lock();
- sd = rcu_dereference_check_sched_domain(this_rq->sd);
- if (sd)
- update_next_balance(sd, &next_balance);
- rcu_read_unlock();
-
- goto out;
- }
-
- raw_spin_unlock(&this_rq->lock);
+ BUG_ON(busiest_rq == target_rq);
- update_blocked_averages(this_cpu);
+ /* Search for an sd spanning us and the target CPU. */
rcu_read_lock();
- for_each_domain(this_cpu, sd) {
- int continue_balancing = 1;
- u64 t0, domain_cost;
-
- if (!(sd->flags & SD_LOAD_BALANCE))
- continue;
-
- if (this_rq->avg_idle < curr_cost + sd->max_newidle_lb_cost) {
- update_next_balance(sd, &next_balance);
- break;
- }
-
- if (sd->flags & SD_BALANCE_NEWIDLE) {
- t0 = sched_clock_cpu(this_cpu);
-
- pulled_task = load_balance(this_cpu, this_rq,
- sd, CPU_NEWLY_IDLE,
- &continue_balancing);
-
- domain_cost = sched_clock_cpu(this_cpu) - t0;
- if (domain_cost > sd->max_newidle_lb_cost)
- sd->max_newidle_lb_cost = domain_cost;
-
- curr_cost += domain_cost;
- }
-
- update_next_balance(sd, &next_balance);
-
- /*
- * Stop searching for tasks to pull if there are
- * now runnable tasks on this rq.
- */
- if (pulled_task || this_rq->nr_running > 0)
- break;
- }
- rcu_read_unlock();
-
- raw_spin_lock(&this_rq->lock);
-
- if (curr_cost > this_rq->max_idle_balance_cost)
- this_rq->max_idle_balance_cost = curr_cost;
-
- /*
- * While browsing the domains, we released the rq lock, a task could
- * have been enqueued in the meantime. Since we're not going idle,
- * pretend we pulled a task.
- */
- if (this_rq->cfs.h_nr_running && !pulled_task)
- pulled_task = 1;
-
-out:
- /* Move the next balance forward */
- if (time_after(this_rq->next_balance, next_balance))
- this_rq->next_balance = next_balance;
-
- /* Is there a task of a high priority class? */
- if (this_rq->nr_running != this_rq->cfs.h_nr_running)
- pulled_task = -1;
-
- if (pulled_task)
- this_rq->idle_stamp = 0;
-
- rq_repin_lock(this_rq, rf);
-
- return pulled_task;
-}
-
-/*
- * active_load_balance_cpu_stop is run by cpu stopper. It pushes
- * running tasks off the busiest CPU onto idle CPUs. It requires at
- * least 1 task to be running on each physical CPU where possible, and
- * avoids physical / logical imbalances.
- */
-static int active_load_balance_cpu_stop(void *data)
-{
- struct rq *busiest_rq = data;
- int busiest_cpu = cpu_of(busiest_rq);
- int target_cpu = busiest_rq->push_cpu;
- struct rq *target_rq = cpu_rq(target_cpu);
- struct sched_domain *sd;
- struct task_struct *p = NULL;
- struct rq_flags rf;
-
- rq_lock_irq(busiest_rq, &rf);
- /*
- * Between queueing the stop-work and running it is a hole in which
- * CPUs can become inactive. We should not move tasks from or to
- * inactive CPUs.
- */
- if (!cpu_active(busiest_cpu) || !cpu_active(target_cpu))
- goto out_unlock;
-
- /* make sure the requested cpu hasn't gone down in the meantime */
- if (unlikely(busiest_cpu != smp_processor_id() ||
- !busiest_rq->active_balance))
- goto out_unlock;
-
- /* Is there any task to move? */
- if (busiest_rq->nr_running <= 1)
- goto out_unlock;
-
- /*
- * This condition is "impossible", if it occurs
- * we need to fix it. Originally reported by
- * Bjorn Helgaas on a 128-cpu setup.
- */
- BUG_ON(busiest_rq == target_rq);
-
- /* Search for an sd spanning us and the target CPU. */
- rcu_read_lock();
- for_each_domain(target_cpu, sd) {
- if ((sd->flags & SD_LOAD_BALANCE) &&
- cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
- break;
- }
+ for_each_domain(target_cpu, sd) {
+ if ((sd->flags & SD_LOAD_BALANCE) &&
+ cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
+ break;
+ }
if (likely(sd)) {
struct lb_env env = {
return 0;
}
-static inline int on_null_domain(struct rq *rq)
-{
- return unlikely(!rcu_dereference_sched(rq->sd));
-}
-
-#ifdef CONFIG_NO_HZ_COMMON
-/*
- * idle load balancing details
- * - When one of the busy CPUs notice that there may be an idle rebalancing
- * needed, they will kick the idle load balancer, which then does idle
- * load balancing for all the idle CPUs.
- */
-static struct {
- cpumask_var_t idle_cpus_mask;
- atomic_t nr_cpus;
- unsigned long next_balance; /* in jiffy units */
-} nohz ____cacheline_aligned;
-
-static inline int find_new_ilb(void)
-{
- int ilb = cpumask_first(nohz.idle_cpus_mask);
-
- if (ilb < nr_cpu_ids && idle_cpu(ilb))
- return ilb;
-
- return nr_cpu_ids;
-}
-
-/*
- * Kick a CPU to do the nohz balancing, if it is time for it. We pick the
- * nohz_load_balancer CPU (if there is one) otherwise fallback to any idle
- * CPU (if there is one).
- */
-static void nohz_balancer_kick(void)
-{
- int ilb_cpu;
-
- nohz.next_balance++;
-
- ilb_cpu = find_new_ilb();
-
- if (ilb_cpu >= nr_cpu_ids)
- return;
-
- if (test_and_set_bit(NOHZ_BALANCE_KICK, nohz_flags(ilb_cpu)))
- return;
- /*
- * Use smp_send_reschedule() instead of resched_cpu().
- * This way we generate a sched IPI on the target cpu which
- * is idle. And the softirq performing nohz idle load balance
- * will be run before returning from the IPI.
- */
- smp_send_reschedule(ilb_cpu);
- return;
-}
-
-void nohz_balance_exit_idle(unsigned int cpu)
-{
- if (unlikely(test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))) {
- /*
- * Completely isolated CPUs don't ever set, so we must test.
- */
- if (likely(cpumask_test_cpu(cpu, nohz.idle_cpus_mask))) {
- cpumask_clear_cpu(cpu, nohz.idle_cpus_mask);
- atomic_dec(&nohz.nr_cpus);
- }
- clear_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
- }
-}
-
-static inline void set_cpu_sd_state_busy(void)
-{
- struct sched_domain *sd;
- int cpu = smp_processor_id();
-
- rcu_read_lock();
- sd = rcu_dereference(per_cpu(sd_llc, cpu));
-
- if (!sd || !sd->nohz_idle)
- goto unlock;
- sd->nohz_idle = 0;
-
- atomic_inc(&sd->shared->nr_busy_cpus);
-unlock:
- rcu_read_unlock();
-}
-
-void set_cpu_sd_state_idle(void)
-{
- struct sched_domain *sd;
- int cpu = smp_processor_id();
-
- rcu_read_lock();
- sd = rcu_dereference(per_cpu(sd_llc, cpu));
-
- if (!sd || sd->nohz_idle)
- goto unlock;
- sd->nohz_idle = 1;
-
- atomic_dec(&sd->shared->nr_busy_cpus);
-unlock:
- rcu_read_unlock();
-}
-
-/*
- * This routine will record that the cpu is going idle with tick stopped.
- * This info will be used in performing idle load balancing in the future.
- */
-void nohz_balance_enter_idle(int cpu)
-{
- /*
- * If this cpu is going down, then nothing needs to be done.
- */
- if (!cpu_active(cpu))
- return;
-
- /* Spare idle load balancing on CPUs that don't want to be disturbed: */
- if (!housekeeping_cpu(cpu, HK_FLAG_SCHED))
- return;
-
- if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))
- return;
-
- /*
- * If we're a completely isolated CPU, we don't play.
- */
- if (on_null_domain(cpu_rq(cpu)))
- return;
-
- cpumask_set_cpu(cpu, nohz.idle_cpus_mask);
- atomic_inc(&nohz.nr_cpus);
- set_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
-}
-#endif
-
static DEFINE_SPINLOCK(balancing);
/*
int need_serialize, need_decay = 0;
u64 max_cost = 0;
- update_blocked_averages(cpu);
-
rcu_read_lock();
for_each_domain(cpu, sd) {
/*
}
}
+static inline int on_null_domain(struct rq *rq)
+{
+ return unlikely(!rcu_dereference_sched(rq->sd));
+}
+
#ifdef CONFIG_NO_HZ_COMMON
/*
- * In CONFIG_NO_HZ_COMMON case, the idle balance kickee will do the
- * rebalancing for all the cpus for whom scheduler ticks are stopped.
+ * idle load balancing details
+ * - When one of the busy CPUs notice that there may be an idle rebalancing
+ * needed, they will kick the idle load balancer, which then does idle
+ * load balancing for all the idle CPUs.
*/
-static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle)
+
+static inline int find_new_ilb(void)
{
- int this_cpu = this_rq->cpu;
- struct rq *rq;
- int balance_cpu;
- /* Earliest time when we have to do rebalance again */
- unsigned long next_balance = jiffies + 60*HZ;
- int update_next_balance = 0;
+ int ilb = cpumask_first(nohz.idle_cpus_mask);
- if (idle != CPU_IDLE ||
- !test_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu)))
- goto end;
+ if (ilb < nr_cpu_ids && idle_cpu(ilb))
+ return ilb;
- for_each_cpu(balance_cpu, nohz.idle_cpus_mask) {
- if (balance_cpu == this_cpu || !idle_cpu(balance_cpu))
- continue;
+ return nr_cpu_ids;
+}
- /*
- * If this cpu gets work to do, stop the load balancing
- * work being done for other cpus. Next load
- * balancing owner will pick it up.
- */
- if (need_resched())
- break;
-
- rq = cpu_rq(balance_cpu);
+/*
+ * Kick a CPU to do the nohz balancing, if it is time for it. We pick the
+ * nohz_load_balancer CPU (if there is one) otherwise fallback to any idle
+ * CPU (if there is one).
+ */
+static void kick_ilb(unsigned int flags)
+{
+ int ilb_cpu;
- /*
- * If time for next balance is due,
- * do the balance.
- */
- if (time_after_eq(jiffies, rq->next_balance)) {
- struct rq_flags rf;
+ nohz.next_balance++;
- rq_lock_irq(rq, &rf);
- update_rq_clock(rq);
- cpu_load_update_idle(rq);
- rq_unlock_irq(rq, &rf);
+ ilb_cpu = find_new_ilb();
- rebalance_domains(rq, CPU_IDLE);
- }
+ if (ilb_cpu >= nr_cpu_ids)
+ return;
- if (time_after(next_balance, rq->next_balance)) {
- next_balance = rq->next_balance;
- update_next_balance = 1;
- }
- }
+ flags = atomic_fetch_or(flags, nohz_flags(ilb_cpu));
+ if (flags & NOHZ_KICK_MASK)
+ return;
/*
- * next_balance will be updated only when there is a need.
- * When the CPU is attached to null domain for ex, it will not be
- * updated.
+ * Use smp_send_reschedule() instead of resched_cpu().
+ * This way we generate a sched IPI on the target CPU which
+ * is idle. And the softirq performing nohz idle load balance
+ * will be run before returning from the IPI.
*/
- if (likely(update_next_balance))
- nohz.next_balance = next_balance;
-end:
- clear_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu));
+ smp_send_reschedule(ilb_cpu);
}
/*
* - For SD_ASYM_PACKING, if the lower numbered cpu's in the scheduler
* domain span are idle.
*/
-static inline bool nohz_kick_needed(struct rq *rq)
+static void nohz_balancer_kick(struct rq *rq)
{
unsigned long now = jiffies;
struct sched_domain_shared *sds;
struct sched_domain *sd;
int nr_busy, i, cpu = rq->cpu;
- bool kick = false;
+ unsigned int flags = 0;
if (unlikely(rq->idle_balance))
- return false;
+ return;
- /*
- * We may be recently in ticked or tickless idle mode. At the first
- * busy tick after returning from idle, we will update the busy stats.
- */
- set_cpu_sd_state_busy();
- nohz_balance_exit_idle(cpu);
+ /*
+ * We may be recently in ticked or tickless idle mode. At the first
+ * busy tick after returning from idle, we will update the busy stats.
+ */
+ nohz_balance_exit_idle(rq);
/*
* None are in tickless mode and hence no need for NOHZ idle load
* balancing.
*/
if (likely(!atomic_read(&nohz.nr_cpus)))
- return false;
+ return;
+
+ if (READ_ONCE(nohz.has_blocked) &&
+ time_after(now, READ_ONCE(nohz.next_blocked)))
+ flags = NOHZ_STATS_KICK;
if (time_before(now, nohz.next_balance))
- return false;
+ goto out;
- if (rq->nr_running >= 2)
- return true;
+ if (rq->nr_running >= 2) {
+ flags = NOHZ_KICK_MASK;
+ goto out;
+ }
rcu_read_lock();
sds = rcu_dereference(per_cpu(sd_llc_shared, cpu));
*/
nr_busy = atomic_read(&sds->nr_busy_cpus);
if (nr_busy > 1) {
- kick = true;
+ flags = NOHZ_KICK_MASK;
goto unlock;
}
if (sd) {
if ((rq->cfs.h_nr_running >= 1) &&
check_cpu_capacity(rq, sd)) {
- kick = true;
+ flags = NOHZ_KICK_MASK;
goto unlock;
}
}
continue;
if (sched_asym_prefer(i, cpu)) {
- kick = true;
+ flags = NOHZ_KICK_MASK;
goto unlock;
}
}
}
unlock:
rcu_read_unlock();
- return kick;
+out:
+ if (flags)
+ kick_ilb(flags);
+}
+
+static void set_cpu_sd_state_busy(int cpu)
+{
+ struct sched_domain *sd;
+
+ rcu_read_lock();
+ sd = rcu_dereference(per_cpu(sd_llc, cpu));
+
+ if (!sd || !sd->nohz_idle)
+ goto unlock;
+ sd->nohz_idle = 0;
+
+ atomic_inc(&sd->shared->nr_busy_cpus);
+unlock:
+ rcu_read_unlock();
+}
+
+void nohz_balance_exit_idle(struct rq *rq)
+{
+ SCHED_WARN_ON(rq != this_rq());
+
+ if (likely(!rq->nohz_tick_stopped))
+ return;
+
+ rq->nohz_tick_stopped = 0;
+ cpumask_clear_cpu(rq->cpu, nohz.idle_cpus_mask);
+ atomic_dec(&nohz.nr_cpus);
+
+ set_cpu_sd_state_busy(rq->cpu);
+}
+
+static void set_cpu_sd_state_idle(int cpu)
+{
+ struct sched_domain *sd;
+
+ rcu_read_lock();
+ sd = rcu_dereference(per_cpu(sd_llc, cpu));
+
+ if (!sd || sd->nohz_idle)
+ goto unlock;
+ sd->nohz_idle = 1;
+
+ atomic_dec(&sd->shared->nr_busy_cpus);
+unlock:
+ rcu_read_unlock();
+}
+
+/*
+ * This routine will record that the CPU is going idle with tick stopped.
+ * This info will be used in performing idle load balancing in the future.
+ */
+void nohz_balance_enter_idle(int cpu)
+{
+ struct rq *rq = cpu_rq(cpu);
+
+ SCHED_WARN_ON(cpu != smp_processor_id());
+
+ /* If this CPU is going down, then nothing needs to be done: */
+ if (!cpu_active(cpu))
+ return;
+
+ /* Spare idle load balancing on CPUs that don't want to be disturbed: */
+ if (!housekeeping_cpu(cpu, HK_FLAG_SCHED))
+ return;
+
+ /*
+ * Can be set safely without rq->lock held
+ * If a clear happens, it will have evaluated last additions because
+ * rq->lock is held during the check and the clear
+ */
+ rq->has_blocked_load = 1;
+
+ /*
+ * The tick is still stopped but load could have been added in the
+ * meantime. We set the nohz.has_blocked flag to trig a check of the
+ * *_avg. The CPU is already part of nohz.idle_cpus_mask so the clear
+ * of nohz.has_blocked can only happen after checking the new load
+ */
+ if (rq->nohz_tick_stopped)
+ goto out;
+
+ /* If we're a completely isolated CPU, we don't play: */
+ if (on_null_domain(rq))
+ return;
+
+ rq->nohz_tick_stopped = 1;
+
+ cpumask_set_cpu(cpu, nohz.idle_cpus_mask);
+ atomic_inc(&nohz.nr_cpus);
+
+ /*
+ * Ensures that if nohz_idle_balance() fails to observe our
+ * @idle_cpus_mask store, it must observe the @has_blocked
+ * store.
+ */
+ smp_mb__after_atomic();
+
+ set_cpu_sd_state_idle(cpu);
+
+out:
+ /*
+ * Each time a cpu enter idle, we assume that it has blocked load and
+ * enable the periodic update of the load of idle cpus
+ */
+ WRITE_ONCE(nohz.has_blocked, 1);
+}
+
+/*
+ * Internal function that runs load balance for all idle cpus. The load balance
+ * can be a simple update of blocked load or a complete load balance with
+ * tasks movement depending of flags.
+ * The function returns false if the loop has stopped before running
+ * through all idle CPUs.
+ */
+static bool _nohz_idle_balance(struct rq *this_rq, unsigned int flags,
+ enum cpu_idle_type idle)
+{
+ /* Earliest time when we have to do rebalance again */
+ unsigned long now = jiffies;
+ unsigned long next_balance = now + 60*HZ;
+ bool has_blocked_load = false;
+ int update_next_balance = 0;
+ int this_cpu = this_rq->cpu;
+ int balance_cpu;
+ int ret = false;
+ struct rq *rq;
+
+ SCHED_WARN_ON((flags & NOHZ_KICK_MASK) == NOHZ_BALANCE_KICK);
+
+ /*
+ * We assume there will be no idle load after this update and clear
+ * the has_blocked flag. If a cpu enters idle in the mean time, it will
+ * set the has_blocked flag and trig another update of idle load.
+ * Because a cpu that becomes idle, is added to idle_cpus_mask before
+ * setting the flag, we are sure to not clear the state and not
+ * check the load of an idle cpu.
+ */
+ WRITE_ONCE(nohz.has_blocked, 0);
+
+ /*
+ * Ensures that if we miss the CPU, we must see the has_blocked
+ * store from nohz_balance_enter_idle().
+ */
+ smp_mb();
+
+ for_each_cpu(balance_cpu, nohz.idle_cpus_mask) {
+ if (balance_cpu == this_cpu || !idle_cpu(balance_cpu))
+ continue;
+
+ /*
+ * If this CPU gets work to do, stop the load balancing
+ * work being done for other CPUs. Next load
+ * balancing owner will pick it up.
+ */
+ if (need_resched()) {
+ has_blocked_load = true;
+ goto abort;
+ }
+
+ rq = cpu_rq(balance_cpu);
+
+ has_blocked_load |= update_nohz_stats(rq, true);
+
+ /*
+ * If time for next balance is due,
+ * do the balance.
+ */
+ if (time_after_eq(jiffies, rq->next_balance)) {
+ struct rq_flags rf;
+
+ rq_lock_irqsave(rq, &rf);
+ update_rq_clock(rq);
+ cpu_load_update_idle(rq);
+ rq_unlock_irqrestore(rq, &rf);
+
+ if (flags & NOHZ_BALANCE_KICK)
+ rebalance_domains(rq, CPU_IDLE);
+ }
+
+ if (time_after(next_balance, rq->next_balance)) {
+ next_balance = rq->next_balance;
+ update_next_balance = 1;
+ }
+ }
+
+ /* Newly idle CPU doesn't need an update */
+ if (idle != CPU_NEWLY_IDLE) {
+ update_blocked_averages(this_cpu);
+ has_blocked_load |= this_rq->has_blocked_load;
+ }
+
+ if (flags & NOHZ_BALANCE_KICK)
+ rebalance_domains(this_rq, CPU_IDLE);
+
+ WRITE_ONCE(nohz.next_blocked,
+ now + msecs_to_jiffies(LOAD_AVG_PERIOD));
+
+ /* The full idle balance loop has been done */
+ ret = true;
+
+abort:
+ /* There is still blocked load, enable periodic update */
+ if (has_blocked_load)
+ WRITE_ONCE(nohz.has_blocked, 1);
+
+ /*
+ * next_balance will be updated only when there is a need.
+ * When the CPU is attached to null domain for ex, it will not be
+ * updated.
+ */
+ if (likely(update_next_balance))
+ nohz.next_balance = next_balance;
+
+ return ret;
+}
+
+/*
+ * In CONFIG_NO_HZ_COMMON case, the idle balance kickee will do the
+ * rebalancing for all the cpus for whom scheduler ticks are stopped.
+ */
+static bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle)
+{
+ int this_cpu = this_rq->cpu;
+ unsigned int flags;
+
+ if (!(atomic_read(nohz_flags(this_cpu)) & NOHZ_KICK_MASK))
+ return false;
+
+ if (idle != CPU_IDLE) {
+ atomic_andnot(NOHZ_KICK_MASK, nohz_flags(this_cpu));
+ return false;
+ }
+
+ /*
+ * barrier, pairs with nohz_balance_enter_idle(), ensures ...
+ */
+ flags = atomic_fetch_andnot(NOHZ_KICK_MASK, nohz_flags(this_cpu));
+ if (!(flags & NOHZ_KICK_MASK))
+ return false;
+
+ _nohz_idle_balance(this_rq, flags, idle);
+
+ return true;
+}
+
+static void nohz_newidle_balance(struct rq *this_rq)
+{
+ int this_cpu = this_rq->cpu;
+
+ /*
+ * This CPU doesn't want to be disturbed by scheduler
+ * housekeeping
+ */
+ if (!housekeeping_cpu(this_cpu, HK_FLAG_SCHED))
+ return;
+
+ /* Will wake up very soon. No time for doing anything else*/
+ if (this_rq->avg_idle < sysctl_sched_migration_cost)
+ return;
+
+ /* Don't need to update blocked load of idle CPUs*/
+ if (!READ_ONCE(nohz.has_blocked) ||
+ time_before(jiffies, READ_ONCE(nohz.next_blocked)))
+ return;
+
+ raw_spin_unlock(&this_rq->lock);
+ /*
+ * This CPU is going to be idle and blocked load of idle CPUs
+ * need to be updated. Run the ilb locally as it is a good
+ * candidate for ilb instead of waking up another idle CPU.
+ * Kick an normal ilb if we failed to do the update.
+ */
+ if (!_nohz_idle_balance(this_rq, NOHZ_STATS_KICK, CPU_NEWLY_IDLE))
+ kick_ilb(NOHZ_STATS_KICK);
+ raw_spin_lock(&this_rq->lock);
+}
+
+#else /* !CONFIG_NO_HZ_COMMON */
+static inline void nohz_balancer_kick(struct rq *rq) { }
+
+static inline bool nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle)
+{
+ return false;
+}
+
+static inline void nohz_newidle_balance(struct rq *this_rq) { }
+#endif /* CONFIG_NO_HZ_COMMON */
+
+/*
+ * idle_balance is called by schedule() if this_cpu is about to become
+ * idle. Attempts to pull tasks from other CPUs.
+ */
+static int idle_balance(struct rq *this_rq, struct rq_flags *rf)
+{
+ unsigned long next_balance = jiffies + HZ;
+ int this_cpu = this_rq->cpu;
+ struct sched_domain *sd;
+ int pulled_task = 0;
+ u64 curr_cost = 0;
+
+ /*
+ * We must set idle_stamp _before_ calling idle_balance(), such that we
+ * measure the duration of idle_balance() as idle time.
+ */
+ this_rq->idle_stamp = rq_clock(this_rq);
+
+ /*
+ * Do not pull tasks towards !active CPUs...
+ */
+ if (!cpu_active(this_cpu))
+ return 0;
+
+ /*
+ * This is OK, because current is on_cpu, which avoids it being picked
+ * for load-balance and preemption/IRQs are still disabled avoiding
+ * further scheduler activity on it and we're being very careful to
+ * re-start the picking loop.
+ */
+ rq_unpin_lock(this_rq, rf);
+
+ if (this_rq->avg_idle < sysctl_sched_migration_cost ||
+ !this_rq->rd->overload) {
+
+ rcu_read_lock();
+ sd = rcu_dereference_check_sched_domain(this_rq->sd);
+ if (sd)
+ update_next_balance(sd, &next_balance);
+ rcu_read_unlock();
+
+ nohz_newidle_balance(this_rq);
+
+ goto out;
+ }
+
+ raw_spin_unlock(&this_rq->lock);
+
+ update_blocked_averages(this_cpu);
+ rcu_read_lock();
+ for_each_domain(this_cpu, sd) {
+ int continue_balancing = 1;
+ u64 t0, domain_cost;
+
+ if (!(sd->flags & SD_LOAD_BALANCE))
+ continue;
+
+ if (this_rq->avg_idle < curr_cost + sd->max_newidle_lb_cost) {
+ update_next_balance(sd, &next_balance);
+ break;
+ }
+
+ if (sd->flags & SD_BALANCE_NEWIDLE) {
+ t0 = sched_clock_cpu(this_cpu);
+
+ pulled_task = load_balance(this_cpu, this_rq,
+ sd, CPU_NEWLY_IDLE,
+ &continue_balancing);
+
+ domain_cost = sched_clock_cpu(this_cpu) - t0;
+ if (domain_cost > sd->max_newidle_lb_cost)
+ sd->max_newidle_lb_cost = domain_cost;
+
+ curr_cost += domain_cost;
+ }
+
+ update_next_balance(sd, &next_balance);
+
+ /*
+ * Stop searching for tasks to pull if there are
+ * now runnable tasks on this rq.
+ */
+ if (pulled_task || this_rq->nr_running > 0)
+ break;
+ }
+ rcu_read_unlock();
+
+ raw_spin_lock(&this_rq->lock);
+
+ if (curr_cost > this_rq->max_idle_balance_cost)
+ this_rq->max_idle_balance_cost = curr_cost;
+
+ /*
+ * While browsing the domains, we released the rq lock, a task could
+ * have been enqueued in the meantime. Since we're not going idle,
+ * pretend we pulled a task.
+ */
+ if (this_rq->cfs.h_nr_running && !pulled_task)
+ pulled_task = 1;
+
+out:
+ /* Move the next balance forward */
+ if (time_after(this_rq->next_balance, next_balance))
+ this_rq->next_balance = next_balance;
+
+ /* Is there a task of a high priority class? */
+ if (this_rq->nr_running != this_rq->cfs.h_nr_running)
+ pulled_task = -1;
+
+ if (pulled_task)
+ this_rq->idle_stamp = 0;
+
+ rq_repin_lock(this_rq, rf);
+
+ return pulled_task;
}
-#else
-static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) { }
-#endif
/*
* run_rebalance_domains is triggered when needed from the scheduler tick.
CPU_IDLE : CPU_NOT_IDLE;
/*
- * If this cpu has a pending nohz_balance_kick, then do the
- * balancing on behalf of the other idle cpus whose ticks are
+ * If this CPU has a pending nohz_balance_kick, then do the
+ * balancing on behalf of the other idle CPUs whose ticks are
* stopped. Do nohz_idle_balance *before* rebalance_domains to
- * give the idle cpus a chance to load balance. Else we may
+ * give the idle CPUs a chance to load balance. Else we may
* load balance only within the local sched_domain hierarchy
* and abort nohz_idle_balance altogether if we pull some load.
*/
- nohz_idle_balance(this_rq, idle);
+ if (nohz_idle_balance(this_rq, idle))
+ return;
+
+ /* normal load balance */
+ update_blocked_averages(this_rq->cpu);
rebalance_domains(this_rq, idle);
}
if (time_after_eq(jiffies, rq->next_balance))
raise_softirq(SCHED_SOFTIRQ);
-#ifdef CONFIG_NO_HZ_COMMON
- if (nohz_kick_needed(rq))
- nohz_balancer_kick();
-#endif
+
+ nohz_balancer_kick(rq);
}
static void rq_online_fair(struct rq *rq)
#endif /* CONFIG_SMP */
/*
- * scheduler tick hitting a task of our scheduling class:
+ * scheduler tick hitting a task of our scheduling class.
+ *
+ * NOTE: This function can be called remotely by the tick offload that
+ * goes along full dynticks. Therefore no local assumption can be made
+ * and everything must be accessed through the @rq and @curr passed in
+ * parameters.
*/
static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued)
{
/* Synchronize entity with its cfs_rq */
update_load_avg(cfs_rq, se, sched_feat(ATTACH_AGE_LOAD) ? 0 : SKIP_AGE_LOAD);
- attach_entity_load_avg(cfs_rq, se);
+ attach_entity_load_avg(cfs_rq, se, 0);
update_tg_load_avg(cfs_rq, false);
propagate_entity_cfs_rq(se);
}
#ifdef CONFIG_NO_HZ_COMMON
nohz.next_balance = jiffies;
+ nohz.next_blocked = jiffies;
zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT);
#endif
#endif /* SMP */
projects / linux-2.6-microblaze.git / blobdiff