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sched/fair: Replace source_load() & target_load() with weighted_cpulo…
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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@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Rik van Riel <riel@surriel.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20190527062116.11512-3-dietmar.eggemann@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Dietmar Eggemann authored and Ingo Molnar committed Jun 3, 2019
1 parent 5e83eaf commit 1c1b8a7
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Showing 2 changed files with 4 additions and 87 deletions.
90 changes: 4 additions & 86 deletions kernel/sched/fair.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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 {
Expand Down Expand Up @@ -5333,45 +5331,11 @@ 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;
Expand Down Expand Up @@ -5479,7 +5443,7 @@ 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);
Expand All @@ -5497,7 +5461,7 @@ 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(prev_cpu));
prev_eff_load -= task_load;
if (sched_feat(WA_BIAS))
prev_eff_load *= 100 + (sd->imbalance_pct - 100) / 2;
Expand Down Expand Up @@ -5558,14 +5522,10 @@ 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;
Expand All @@ -5589,12 +5549,7 @@ 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);
Expand Down Expand Up @@ -7676,34 +7631,6 @@ 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);
Expand Down Expand Up @@ -7992,9 +7919,6 @@ 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));
Expand All @@ -8005,13 +7929,7 @@ 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;

Expand Down
1 change: 0 additions & 1 deletion kernel/sched/features.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down

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