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sched/fair: Always update CPU capacity when load balancing

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Limiting CPU capacity updates, which are quite cheap, results in worse
balancing decisions during opportunistic balancing (e.g., SD_BALANCE_WAKE).
This causes opportunistic placement decisions to be skewed using stale CPU
capacity data, and when a CPU isn't idling much, its capacity suffers from
even more staleness since the only exception to the 100 ms capacity update
ratelimit is a CPU exiting idle.

Since the capacity updates are cheap, always do it when load balancing in
order to improve opportunistic task placement decisions.

Change-Id: If1d451ce742fd093010057e31e71012d47fad70a
Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>
This commit is contained in:
Sultan Alsawaf 2023-07-04 20:46:18 -07:00 committed by Ksawlii
parent 323a4009a4
commit fa6b06bf46
1 changed files with 0 additions and 9 deletions
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9
kernel/sched/fair.c
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@ -8535,11 +8535,6 @@ void update_group_capacity(struct sched_domain *sd, int cpu)
struct sched_domain *child = sd->child;
struct sched_group *group, *sdg = sd->groups;
unsigned long capacity, min_capacity, max_capacity;
unsigned long interval;
interval = msecs_to_jiffies(sd->balance_interval);
interval = clamp(interval, 1UL, max_load_balance_interval);
sdg->sgc->next_update = jiffies + interval;
if (!child) {
update_cpu_capacity(sd, cpu);
@ -9331,10 +9326,6 @@ static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sd
if (local_group) {
sds->local = sg;
sgs = local;
if (env->idle != CPU_NEWLY_IDLE ||
time_after_eq(jiffies, sg->sgc->next_update))
update_group_capacity(env->sd, env->dst_cpu);
}
update_sg_lb_stats(env, sg, sgs, &sg_status);