Old code considers the bias in source/target_load already. but still use imbalance_pct as last check in idlest/busiest group finding. It is also a kind of redundant job. If we bias imbalance in source/target_load, we'd better not use imbalance_pct again.
After cpu_load array removed, it is nice time to unify the target bias consideration. So I remove the imbalance_pct from last check and add the live bias using.
On wake_affine, since all archs' wake_idx is 0, current logical is just want to prefer current cpu. so we follows this logical. Just renaming the target_load/source_load to wegithed_cpuload for more exact meaning. Thanks for reminding from Morten!
Signed-off-by: Alex Shi alex.shi@linaro.org --- kernel/sched/fair.c | 32 +++++++++++++++----------------- 1 file changed, 15 insertions(+), 17 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index eeffe75..5a3ea72 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1016,7 +1016,7 @@ bool should_numa_migrate_memory(struct task_struct *p, struct page * page,
static unsigned long weighted_cpuload(const int cpu); static unsigned long source_load(int cpu); -static unsigned long target_load(int cpu); +static unsigned long target_load(int cpu, int imbalance_pct); static unsigned long power_of(int cpu); static long effective_load(struct task_group *tg, int cpu, long wl, long wg);
@@ -3967,7 +3967,7 @@ static unsigned long source_load(int cpu) * 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) +static unsigned long target_load(int cpu, int imbalance_pct) { struct rq *rq = cpu_rq(cpu); unsigned long total = weighted_cpuload(cpu); @@ -3975,6 +3975,11 @@ static unsigned long target_load(int cpu) if (!sched_feat(LB_BIAS)) return total;
+ /* + * Bias target load with imbalance_pct. + */ + total = total * imbalance_pct / 100; + return max(rq->cpu_load, total); }
@@ -4190,8 +4195,8 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
this_cpu = smp_processor_id(); prev_cpu = task_cpu(p); - load = source_load(prev_cpu); - this_load = target_load(this_cpu); + load = weighted_cpuload(prev_cpu); + this_load = weighted_cpuload(this_cpu);
/* * If sync wakeup then subtract the (maximum possible) @@ -4247,7 +4252,7 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
if (balanced || (this_load <= load && - this_load + target_load(prev_cpu) <= tl_per_task)) { + this_load + weighted_cpuload(prev_cpu) <= tl_per_task)) { /* * This domain has SD_WAKE_AFFINE and * p is cache cold in this domain, and @@ -4293,7 +4298,7 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu) if (local_group) load = source_load(i); else - load = target_load(i); + load = target_load(i, imbalance);
avg_load += load; } @@ -4309,7 +4314,7 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu) } } while (group = group->next, group != sd->groups);
- if (!idlest || 100*this_load < imbalance*min_load) + if (!idlest || this_load < min_load) return NULL; return idlest; } @@ -5745,6 +5750,7 @@ static inline void update_sg_lb_stats(struct lb_env *env, { unsigned long load; int i; + int bias = 100 + (env->sd->imbalance_pct - 100) / 2;
memset(sgs, 0, sizeof(*sgs));
@@ -5752,8 +5758,8 @@ static inline void update_sg_lb_stats(struct lb_env *env, struct rq *rq = cpu_rq(i);
/* Bias balancing toward cpus of our domain */ - if (local_group) - load = target_load(i); + if (local_group && env->idle != CPU_IDLE) + load = target_load(i, bias); else load = source_load(i);
@@ -6193,14 +6199,6 @@ static struct sched_group *find_busiest_group(struct lb_env *env) if ((local->idle_cpus < busiest->idle_cpus) && busiest->sum_nr_running <= busiest->group_weight) goto out_balanced; - } else { - /* - * In the CPU_NEWLY_IDLE, CPU_NOT_IDLE cases, use - * imbalance_pct to be conservative. - */ - if (100 * busiest->avg_load <= - env->sd->imbalance_pct * local->avg_load) - goto out_balanced; }
force_balance: