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Message-Id: <20190527062116.11512-3-dietmar.eggemann@arm.com>
Date: Mon, 27 May 2019 07:21:11 +0100
From: Dietmar Eggemann <dietmar.eggemann@....com>
To: Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...nel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>,
Frederic Weisbecker <fweisbec@...il.com>,
Rik van Riel <riel@...riel.com>,
Vincent Guittot <vincent.guittot@...aro.org>,
Morten Rasmussen <morten.rasmussen@....com>,
Quentin Perret <quentin.perret@....com>,
Valentin Schneider <valentin.schneider@....com>,
Patrick Bellasi <patrick.bellasi@....com>,
linux-kernel@...r.kernel.org
Subject: [PATCH 2/7] sched/fair: Replace source_load() & target_load() w/ weighted_cpuload()
With LB_BIAS disabled, source_load() & target_load() return
weighted_cpuload(). Replace both with calls to weighted_cpuload().
The function to obtain the load index (sd->*_idx) for an sd,
get_sd_load_idx(), can be removed as well.
Finally, get rid of the sched feature LB_BIAS.
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@....com>
---
kernel/sched/fair.c | 90 ++---------------------------------------
kernel/sched/features.h | 1 -
2 files changed, 4 insertions(+), 87 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index f619b93ca331..88779c45e8e6 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1467,8 +1467,6 @@ bool should_numa_migrate_memory(struct task_struct *p, struct page * page,
}
static unsigned long weighted_cpuload(struct rq *rq);
-static unsigned long source_load(int cpu, int type);
-static unsigned long target_load(int cpu, int type);
/* Cached statistics for all CPUs within a node */
struct numa_stats {
@@ -5336,45 +5334,11 @@ static struct {
#endif /* CONFIG_NO_HZ_COMMON */
-/* Used instead of source_load when we know the type == 0 */
static unsigned long weighted_cpuload(struct rq *rq)
{
return cfs_rq_runnable_load_avg(&rq->cfs);
}
-/*
- * 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
- * balance conservatively.
- */
-static unsigned long source_load(int cpu, int type)
-{
- struct rq *rq = cpu_rq(cpu);
- unsigned long total = weighted_cpuload(rq);
-
- if (type == 0 || !sched_feat(LB_BIAS))
- return total;
-
- return min(rq->cpu_load[type-1], total);
-}
-
-/*
- * 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)
-{
- struct rq *rq = cpu_rq(cpu);
- unsigned long total = weighted_cpuload(rq);
-
- if (type == 0 || !sched_feat(LB_BIAS))
- return total;
-
- return max(rq->cpu_load[type-1], total);
-}
-
static unsigned long capacity_of(int cpu)
{
return cpu_rq(cpu)->cpu_capacity;
@@ -5482,7 +5446,7 @@ wake_affine_weight(struct sched_domain *sd, struct task_struct *p,
s64 this_eff_load, prev_eff_load;
unsigned long task_load;
- this_eff_load = target_load(this_cpu, sd->wake_idx);
+ this_eff_load = weighted_cpuload(cpu_rq(this_cpu));
if (sync) {
unsigned long current_load = task_h_load(current);
@@ -5500,7 +5464,7 @@ wake_affine_weight(struct sched_domain *sd, struct task_struct *p,
this_eff_load *= 100;
this_eff_load *= capacity_of(prev_cpu);
- prev_eff_load = source_load(prev_cpu, sd->wake_idx);
+ prev_eff_load = weighted_cpuload(cpu_rq(this_cpu));
prev_eff_load -= task_load;
if (sched_feat(WA_BIAS))
prev_eff_load *= 100 + (sd->imbalance_pct - 100) / 2;
@@ -5561,14 +5525,10 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p,
unsigned long this_runnable_load = ULONG_MAX;
unsigned long min_avg_load = ULONG_MAX, this_avg_load = ULONG_MAX;
unsigned long most_spare = 0, this_spare = 0;
- int load_idx = sd->forkexec_idx;
int imbalance_scale = 100 + (sd->imbalance_pct-100)/2;
unsigned long imbalance = scale_load_down(NICE_0_LOAD) *
(sd->imbalance_pct-100) / 100;
- if (sd_flag & SD_BALANCE_WAKE)
- load_idx = sd->wake_idx;
-
do {
unsigned long load, avg_load, runnable_load;
unsigned long spare_cap, max_spare_cap;
@@ -5592,12 +5552,7 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p,
max_spare_cap = 0;
for_each_cpu(i, sched_group_span(group)) {
- /* Bias balancing toward CPUs of our domain */
- if (local_group)
- load = source_load(i, load_idx);
- else
- load = target_load(i, load_idx);
-
+ load = weighted_cpuload(cpu_rq(i));
runnable_load += load;
avg_load += cfs_rq_load_avg(&cpu_rq(i)->cfs);
@@ -7679,34 +7634,6 @@ static inline void init_sd_lb_stats(struct sd_lb_stats *sds)
};
}
-/**
- * get_sd_load_idx - Obtain the load index for a given sched domain.
- * @sd: The sched_domain whose load_idx is to be obtained.
- * @idle: The idle status of the CPU for whose sd load_idx is obtained.
- *
- * Return: The load index.
- */
-static inline int get_sd_load_idx(struct sched_domain *sd,
- enum cpu_idle_type idle)
-{
- int load_idx;
-
- switch (idle) {
- case CPU_NOT_IDLE:
- load_idx = sd->busy_idx;
- break;
-
- case CPU_NEWLY_IDLE:
- load_idx = sd->newidle_idx;
- break;
- default:
- load_idx = sd->idle_idx;
- break;
- }
-
- return load_idx;
-}
-
static unsigned long scale_rt_capacity(struct sched_domain *sd, int cpu)
{
struct rq *rq = cpu_rq(cpu);
@@ -7995,9 +7922,6 @@ static inline void update_sg_lb_stats(struct lb_env *env,
struct sg_lb_stats *sgs,
int *sg_status)
{
- int local_group = cpumask_test_cpu(env->dst_cpu, sched_group_span(group));
- int load_idx = get_sd_load_idx(env->sd, env->idle);
- unsigned long load;
int i, nr_running;
memset(sgs, 0, sizeof(*sgs));
@@ -8008,13 +7932,7 @@ static inline void update_sg_lb_stats(struct lb_env *env,
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
- load = source_load(i, load_idx);
-
- sgs->group_load += load;
+ sgs->group_load += weighted_cpuload(rq);
sgs->group_util += cpu_util(i);
sgs->sum_nr_running += rq->cfs.h_nr_running;
diff --git a/kernel/sched/features.h b/kernel/sched/features.h
index 858589b83377..2410db5e9a35 100644
--- a/kernel/sched/features.h
+++ b/kernel/sched/features.h
@@ -39,7 +39,6 @@ SCHED_FEAT(WAKEUP_PREEMPTION, true)
SCHED_FEAT(HRTICK, false)
SCHED_FEAT(DOUBLE_TICK, false)
-SCHED_FEAT(LB_BIAS, false)
/*
* Decrement CPU capacity based on time not spent running tasks
--
2.17.1
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