sched/fair: Restructure wake_affine*() to return a CPU id
This is a preparation patch that has wake_affine*() return a CPU ID instead of a boolean. The intent is to allow the wake_affine() helpers to be avoided if a decision is already made. This patch has no functional change. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20180130104555.4125-3-mgorman@techsingularity.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -5692,7 +5692,7 @@ static int wake_wide(struct task_struct *p)
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* scheduling latency of the CPUs. This seems to work
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* for the overloaded case.
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*/
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static bool
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static int
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wake_affine_idle(int this_cpu, int prev_cpu, int sync)
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{
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/*
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@ -5702,15 +5702,15 @@ wake_affine_idle(int this_cpu, int prev_cpu, int sync)
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* node depending on the IO topology or IRQ affinity settings.
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*/
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if (idle_cpu(this_cpu) && cpus_share_cache(this_cpu, prev_cpu))
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return true;
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return this_cpu;
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if (sync && cpu_rq(this_cpu)->nr_running == 1)
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return true;
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return this_cpu;
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return false;
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return nr_cpumask_bits;
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}
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static bool
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static int
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wake_affine_weight(struct sched_domain *sd, struct task_struct *p,
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int this_cpu, int prev_cpu, int sync)
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{
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@ -5724,7 +5724,7 @@ wake_affine_weight(struct sched_domain *sd, struct task_struct *p,
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unsigned long current_load = task_h_load(current);
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if (current_load > this_eff_load)
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return true;
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return this_cpu;
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this_eff_load -= current_load;
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}
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@ -5741,28 +5741,28 @@ wake_affine_weight(struct sched_domain *sd, struct task_struct *p,
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prev_eff_load *= 100 + (sd->imbalance_pct - 100) / 2;
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prev_eff_load *= capacity_of(this_cpu);
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return this_eff_load <= prev_eff_load;
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return this_eff_load <= prev_eff_load ? this_cpu : nr_cpumask_bits;
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}
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static int wake_affine(struct sched_domain *sd, struct task_struct *p,
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int prev_cpu, int sync)
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{
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int this_cpu = smp_processor_id();
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bool affine = false;
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int target = nr_cpumask_bits;
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if (sched_feat(WA_IDLE))
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affine = wake_affine_idle(this_cpu, prev_cpu, sync);
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target = wake_affine_idle(this_cpu, prev_cpu, sync);
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if (sched_feat(WA_WEIGHT) && !affine)
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affine = wake_affine_weight(sd, p, this_cpu, prev_cpu, sync);
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if (sched_feat(WA_WEIGHT) && target == nr_cpumask_bits)
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target = wake_affine_weight(sd, p, this_cpu, prev_cpu, sync);
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schedstat_inc(p->se.statistics.nr_wakeups_affine_attempts);
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if (affine) {
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if (target == nr_cpumask_bits)
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return prev_cpu;
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schedstat_inc(sd->ttwu_move_affine);
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schedstat_inc(p->se.statistics.nr_wakeups_affine);
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}
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return affine;
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return target;
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}
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static inline unsigned long task_util(struct task_struct *p);
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@ -6355,8 +6355,7 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f
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if (cpu == prev_cpu)
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goto pick_cpu;
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if (wake_affine(affine_sd, p, prev_cpu, sync))
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new_cpu = cpu;
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new_cpu = wake_affine(affine_sd, p, prev_cpu, sync);
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}
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if (sd && !(sd_flag & SD_BALANCE_FORK)) {
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