On Tue, Mar 02, 2021 at 11:59:39AM +1300, Barry Song wrote:
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 88a2e2b..d805e59 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7797,6 +7797,16 @@ int sched_cpu_activate(unsigned int cpu) if (cpumask_weight(cpu_smt_mask(cpu)) == 2) static_branch_inc_cpuslocked(&sched_smt_present); #endif + +#ifdef CONFIG_SCHED_CLUSTER + /* + * When going up, increment the number of cluster cpus with + * cluster present. + */ + if (cpumask_weight(cpu_cluster_mask(cpu)) > 1) + static_branch_inc_cpuslocked(&sched_cluster_present); +#endif + set_cpu_active(cpu, true);
if (sched_smp_initialized) { @@ -7873,6 +7883,14 @@ int sched_cpu_deactivate(unsigned int cpu) static_branch_dec_cpuslocked(&sched_smt_present); #endif
+#ifdef CONFIG_SCHED_CLUSTER + /* + * When going down, decrement the number of cpus with cluster present. + */ + if (cpumask_weight(cpu_cluster_mask(cpu)) > 1) + static_branch_dec_cpuslocked(&sched_cluster_present); +#endif + if (!sched_smp_initialized) return 0;
I don't think that's correct. IIUC this will mean the sched_cluster_present thing will be enabled on anything with SMT (very much including x86 big cores after the next patch). I'm thinking that at the very least you should check a CLS domain exists, but that might be hard at this point, because the sched domains haven't been build yet.
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 8a8bd7b..3db7b07 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6009,6 +6009,11 @@ static inline int __select_idle_cpu(int cpu) return -1; }
+#ifdef CONFIG_SCHED_CLUSTER +DEFINE_STATIC_KEY_FALSE(sched_cluster_present); +EXPORT_SYMBOL_GPL(sched_cluster_present);
I really rather think this shouldn't be exported
+#endif + #ifdef CONFIG_SCHED_SMT DEFINE_STATIC_KEY_FALSE(sched_smt_present); EXPORT_SYMBOL_GPL(sched_smt_present);
This is a KVM wart, it needs to know because mitigation crap.
@@ -6116,6 +6121,26 @@ static inline int select_idle_core(struct task_struct *p, int core, struct cpuma
#endif /* CONFIG_SCHED_SMT */
+static inline int _select_idle_cpu(bool smt, struct task_struct *p, int target, struct cpumask *cpus, int *idle_cpu, int *nr) +{ + int cpu, i; + + for_each_cpu_wrap(cpu, cpus, target) { + if (smt) { + i = select_idle_core(p, cpu, cpus, idle_cpu); + } else { + if (!--*nr) + return -1; + i = __select_idle_cpu(cpu); + } + + if ((unsigned int)i < nr_cpumask_bits) + return i; + } + + return -1; +} + /* * Scan the LLC domain for idle CPUs; this is dynamically regulated by * comparing the average scan cost (tracked in sd->avg_scan_cost) against the @@ -6124,7 +6149,7 @@ static inline int select_idle_core(struct task_struct *p, int core, struct cpuma static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int target) { struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_idle_mask); - int i, cpu, idle_cpu = -1, nr = INT_MAX; + int i, idle_cpu = -1, nr = INT_MAX; bool smt = test_idle_cores(target, false); int this = smp_processor_id(); struct sched_domain *this_sd; @@ -6134,7 +6159,12 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t if (!this_sd) return -1;
- cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr); + if (!sched_cluster_active()) + cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr); +#ifdef CONFIG_SCHED_CLUSTER + if (sched_cluster_active()) + cpumask_and(cpus, cpu_cluster_mask(target), p->cpus_ptr); +#endif
if (sched_feat(SIS_PROP) && !smt) { u64 avg_cost, avg_idle, span_avg; @@ -6155,24 +6185,32 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t time = cpu_clock(this); }
- for_each_cpu_wrap(cpu, cpus, target) { - if (smt) { - i = select_idle_core(p, cpu, cpus, &idle_cpu); - if ((unsigned int)i < nr_cpumask_bits) - return i; + /* scan cluster before scanning the whole llc */ +#ifdef CONFIG_SCHED_CLUSTER + if (sched_cluster_active()) { + i = _select_idle_cpu(smt, p, target, cpus, &idle_cpu, &nr); + if ((unsigned int) i < nr_cpumask_bits) { + idle_cpu = i; + goto done; + } else if (nr <= 0) + return -1;
- } else { - if (!--nr) - return -1; - idle_cpu = __select_idle_cpu(cpu); - if ((unsigned int)idle_cpu < nr_cpumask_bits) - break; - } + cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr); + cpumask_andnot(cpus, cpus, cpu_cluster_mask(target)); } +#endif + + i = _select_idle_cpu(smt, p, target, cpus, &idle_cpu, &nr); + if ((unsigned int) i < nr_cpumask_bits) { + idle_cpu = i; + goto done; + } else if (nr <= 0) + return -1;
if (smt) set_idle_cores(this, false);
+done: if (sched_feat(SIS_PROP) && !smt) { time = cpu_clock(this) - time; update_avg(&this_sd->avg_scan_cost, time);
And this is just horrific :-(