sched/topology: Provide cfs_overload_cpus bitmap

hulk inclusion
category: feature
bugzilla: 38261, https://bugzilla.openeuler.org/show_bug.cgi?id=23
CVE: NA

---------------------------

Define and initialize a sparse bitmap of overloaded CPUs, per
last-level-cache scheduling domain, for use by the CFS scheduling class.
Save a pointer to cfs_overload_cpus in the rq for efficient access.
Signed-off-by: NSteve Sistare <steven.sistare@oracle.com>
Signed-off-by: NCheng Jian <cj.chengjian@huawei.com>
Reviewed-by: NHanjun Guo <guohanjun@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Reviewed-by: NXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

include/linux/sched/topology.h

@@ -72,6 +72,7 @@ struct sched_domain_shared {
 	atomic_t	ref;
 	atomic_t	nr_busy_cpus;
 	int		has_idle_cores;
+	struct sparsemask *cfs_overload_cpus;
 };
 
 struct sched_domain {

kernel/sched/sched.h

@@ -83,6 +83,7 @@
 
 struct rq;
 struct cpuidle_state;
+struct sparsemask;
 
 /* task_struct::on_rq states: */
 #define TASK_ON_RQ_QUEUED	1
@@ -829,6 +830,7 @@ struct rq {
 	struct cfs_rq		cfs;
 	struct rt_rq		rt;
 	struct dl_rq		dl;
+	struct sparsemask	*cfs_overload_cpus;
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
 	/* list of leaf cfs_rq on this CPU: */

kernel/sched/topology.c

@@ -3,6 +3,7 @@
  * Scheduler topology setup/handling methods
  */
 #include "sched.h"
+#include "sparsemask.h"
 
 DEFINE_MUTEX(sched_domains_mutex);
 
@@ -409,7 +410,9 @@ DEFINE_PER_CPU(struct sched_domain *, sd_asym);
 
 static void update_top_cache_domain(int cpu)
 {
+	struct sparsemask *cfs_overload_cpus = NULL;
 	struct sched_domain_shared *sds = NULL;
+	struct rq *rq = cpu_rq(cpu);
 	struct sched_domain *sd;
 	int id = cpu;
 	int size = 1;
@@ -419,8 +422,10 @@ static void update_top_cache_domain(int cpu)
 		id = cpumask_first(sched_domain_span(sd));
 		size = cpumask_weight(sched_domain_span(sd));
 		sds = sd->shared;
+		cfs_overload_cpus = sds->cfs_overload_cpus;
 	}
 
+	rcu_assign_pointer(rq->cfs_overload_cpus, cfs_overload_cpus);
 	rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
 	per_cpu(sd_llc_size, cpu) = size;
 	per_cpu(sd_llc_id, cpu) = id;
@@ -1613,7 +1618,22 @@ static void __sdt_free(const struct cpumask *cpu_map)
 
 static int sd_llc_alloc(struct sched_domain *sd)
 {
-	/* Allocate sd->shared data here. Empty for now. */
+	struct sched_domain_shared *sds = sd->shared;
+	struct cpumask *span = sched_domain_span(sd);
+	int nid = cpu_to_node(cpumask_first(span));
+	int flags = __GFP_ZERO | GFP_KERNEL;
+	struct sparsemask *mask;
+
+	/*
+	 * Allocate the bitmap if not already allocated.  This is called for
+	 * every CPU in the LLC but only allocates once per sd_llc_shared.
+	 */
+	if (!sds->cfs_overload_cpus) {
+		mask = sparsemask_alloc_node(nr_cpu_ids, 3, flags, nid);
+		if (!mask)
+			return 1;
+		sds->cfs_overload_cpus = mask;
+	}
 
 	return 0;
 }
@@ -1625,7 +1645,8 @@ static void sd_llc_free(struct sched_domain *sd)
 	if (!sds)
 		return;
 
-	/* Free data here. Empty for now. */
+	sparsemask_free(sds->cfs_overload_cpus);
+	sds->cfs_overload_cpus = NULL;
 }
 
 static int sd_llc_alloc_all(const struct cpumask *cpu_map, struct s_data *d)