sched/fair: Merge select_idle_core/cpu()
Both select_idle_core() and select_idle_cpu() do a loop over the same cpumask. Observe that by clearing the already visited CPUs, we can fold the iteration and iterate a core at a time. All we need to do is remember any non-idle CPU we encountered while scanning for an idle core. This way we'll only iterate every CPU once. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org> Link: https://lkml.kernel.org/r/20210127135203.19633-5-mgorman@techsingularity.net
This commit is contained in:
Mel Gorman
Ingo Molnar
Родитель
6cd56ef1df
Коммит
9fe1f127b9
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@ -6019,6 +6019,14 @@ static inline int find_idlest_cpu(struct sched_domain *sd, struct task_struct *p
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return new_cpu;
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}
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static inline int __select_idle_cpu(int cpu)
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{
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if (available_idle_cpu(cpu) || sched_idle_cpu(cpu))
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return cpu;
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return -1;
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}
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#ifdef CONFIG_SCHED_SMT
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DEFINE_STATIC_KEY_FALSE(sched_smt_present);
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EXPORT_SYMBOL_GPL(sched_smt_present);
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@ -6077,48 +6085,51 @@ unlock:
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* there are no idle cores left in the system; tracked through
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* sd_llc->shared->has_idle_cores and enabled through update_idle_core() above.
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*/
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static int select_idle_core(struct task_struct *p, struct sched_domain *sd, int target)
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static int select_idle_core(struct task_struct *p, int core, struct cpumask *cpus, int *idle_cpu)
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{
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struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_idle_mask);
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int core, cpu;
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bool idle = true;
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int cpu;
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if (!static_branch_likely(&sched_smt_present))
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return -1;
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return __select_idle_cpu(core);
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if (!test_idle_cores(target, false))
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return -1;
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cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr);
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for_each_cpu_wrap(core, cpus, target) {
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bool idle = true;
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for_each_cpu(cpu, cpu_smt_mask(core)) {
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if (!available_idle_cpu(cpu)) {
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idle = false;
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break;
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for_each_cpu(cpu, cpu_smt_mask(core)) {
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if (!available_idle_cpu(cpu)) {
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idle = false;
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if (*idle_cpu == -1) {
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if (sched_idle_cpu(cpu) && cpumask_test_cpu(cpu, p->cpus_ptr)) {
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*idle_cpu = cpu;
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break;
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}
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continue;
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}
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break;
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}
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if (idle)
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return core;
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cpumask_andnot(cpus, cpus, cpu_smt_mask(core));
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if (*idle_cpu == -1 && cpumask_test_cpu(cpu, p->cpus_ptr))
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*idle_cpu = cpu;
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}
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/*
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* Failed to find an idle core; stop looking for one.
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*/
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set_idle_cores(target, 0);
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if (idle)
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return core;
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cpumask_andnot(cpus, cpus, cpu_smt_mask(core));
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return -1;
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}
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#else /* CONFIG_SCHED_SMT */
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static inline int select_idle_core(struct task_struct *p, struct sched_domain *sd, int target)
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static inline void set_idle_cores(int cpu, int val)
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{
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return -1;
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}
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static inline bool test_idle_cores(int cpu, bool def)
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{
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return def;
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}
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static inline int select_idle_core(struct task_struct *p, int core, struct cpumask *cpus, int *idle_cpu)
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{
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return __select_idle_cpu(core);
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}
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#endif /* CONFIG_SCHED_SMT */
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@ -6131,10 +6142,11 @@ static inline int select_idle_core(struct task_struct *p, struct sched_domain *s
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static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int target)
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{
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struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_idle_mask);
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int i, cpu, idle_cpu = -1, nr = INT_MAX;
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bool smt = test_idle_cores(target, false);
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int this = smp_processor_id();
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struct sched_domain *this_sd;
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u64 time;
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int this = smp_processor_id();
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int cpu, nr = INT_MAX;
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this_sd = rcu_dereference(*this_cpu_ptr(&sd_llc));
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if (!this_sd)
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@ -6142,7 +6154,7 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t
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cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr);
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if (sched_feat(SIS_PROP)) {
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if (sched_feat(SIS_PROP) && !smt) {
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u64 avg_cost, avg_idle, span_avg;
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/*
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@ -6162,18 +6174,29 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t
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}
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for_each_cpu_wrap(cpu, cpus, target) {
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if (!--nr)
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return -1;
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if (available_idle_cpu(cpu) || sched_idle_cpu(cpu))
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break;
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if (smt) {
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i = select_idle_core(p, cpu, cpus, &idle_cpu);
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if ((unsigned int)i < nr_cpumask_bits)
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return i;
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} else {
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if (!--nr)
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return -1;
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idle_cpu = __select_idle_cpu(cpu);
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if ((unsigned int)idle_cpu < nr_cpumask_bits)
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break;
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}
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}
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if (sched_feat(SIS_PROP)) {
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if (smt)
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set_idle_cores(this, false);
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if (sched_feat(SIS_PROP) && !smt) {
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time = cpu_clock(this) - time;
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update_avg(&this_sd->avg_scan_cost, time);
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}
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return cpu;
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return idle_cpu;
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}
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/*
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@ -6302,10 +6325,6 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target)
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if (!sd)
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return target;
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i = select_idle_core(p, sd, target);
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if ((unsigned)i < nr_cpumask_bits)
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return i;
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i = select_idle_cpu(p, sd, target);
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if ((unsigned)i < nr_cpumask_bits)
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return i;
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