linux-kernel - [RFC PATCH 5/7] sched/topology: Make {lowest/highest}_flag

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Date:   Wed, 11 Dec 2019 16:43:59 +0000
From:   Valentin Schneider <valentin.schneider@....com>
To:     linux-kernel@...r.kernel.org
Cc:     mingo@...hat.com, peterz@...radead.org, vincent.guittot@...aro.org,
        dietmar.eggemann@....com
Subject: [RFC PATCH 5/7] sched/topology: Make {lowest/highest}_flag_domain() work with > 1 flags

In some cases, select_task_rq_fair() ends up looking for the highest domain
with both SD_LOAD_BALANCE and one of SD_BALANCE_{WAKE, FORK, EXEC}.
This is pretty much a highest_flag_domain() call, but that latter
can only cope with a single flag.

Make the existing helpers cope with being passed more than one flag. While
at it, rename them to make their newfound powers explicit.

Signed-off-by: Valentin Schneider <valentin.schneider@....com>
---
 kernel/sched/sched.h    | 23 ++++++++++++++++-------
 kernel/sched/topology.c |  8 ++++----
 2 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 62efc0443cac..233b3d41e347 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1340,20 +1340,20 @@ extern void sched_ttwu_pending(void);
 #define for_each_lower_domain(sd) for (; sd; sd = sd->child)
 
 /**
- * highest_flag_domain - Return highest sched_domain containing flag.
+ * highest_flags_domain - Return highest sched_domain containing flags.
  * @cpu:	The CPU whose highest level of sched domain is to
  *		be returned.
- * @flag:	The flag to check for the highest sched_domain
+ * @flags:	The flags to check for the highest sched_domain
  *		for the given CPU.
  *
- * Returns the highest sched_domain of a CPU which contains the given flag.
+ * Returns the highest sched_domain of a CPU which contains all given flags.
  */
-static inline struct sched_domain *highest_flag_domain(int cpu, int flag)
+static inline struct sched_domain *highest_flags_domain(int cpu, int flags)
 {
 	struct sched_domain *sd, *hsd = NULL;
 
 	for_each_domain(cpu, sd) {
-		if (!(sd->flags & flag))
+		if (!((sd->flags & flags) == flags))
 			break;
 		hsd = sd;
 	}
@@ -1361,12 +1361,21 @@ static inline struct sched_domain *highest_flag_domain(int cpu, int flag)
 	return hsd;
 }
 
-static inline struct sched_domain *lowest_flag_domain(int cpu, int flag)
+/**
+ * lowest_flags_domain - Return lowest sched_domain containing flags.
+ * @cpu:	The CPU whose lowest level of sched domain is to
+ *		be returned.
+ * @flags:	The flags to check for the lowest sched_domain
+ *		for the given CPU.
+ *
+ * Returns the lowest sched_domain of a CPU which contains all given flags.
+ */
+static inline struct sched_domain *lowest_flags_domain(int cpu, int flags)
 {
 	struct sched_domain *sd;
 
 	for_each_domain(cpu, sd) {
-		if (sd->flags & flag)
+		if ((sd->flags & flags) == flags)
 			break;
 	}
 
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 6ec1e595b1d4..f0d2a15fd10b 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -631,7 +631,7 @@ static void update_top_cache_domain(int cpu)
 	int id = cpu;
 	int size = 1;
 
-	sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
+	sd = highest_flags_domain(cpu, SD_SHARE_PKG_RESOURCES);
 	if (sd) {
 		id = cpumask_first(sched_domain_span(sd));
 		size = cpumask_weight(sched_domain_span(sd));
@@ -643,13 +643,13 @@ static void update_top_cache_domain(int cpu)
 	per_cpu(sd_llc_id, cpu) = id;
 	rcu_assign_pointer(per_cpu(sd_llc_shared, cpu), sds);
 
-	sd = lowest_flag_domain(cpu, SD_NUMA);
+	sd = lowest_flags_domain(cpu, SD_NUMA);
 	rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
 
-	sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
+	sd = highest_flags_domain(cpu, SD_ASYM_PACKING);
 	rcu_assign_pointer(per_cpu(sd_asym_packing, cpu), sd);
 
-	sd = lowest_flag_domain(cpu, SD_ASYM_CPUCAPACITY);
+	sd = lowest_flags_domain(cpu, SD_ASYM_CPUCAPACITY);
 	rcu_assign_pointer(per_cpu(sd_asym_cpucapacity, cpu), sd);
 }
 
-- 
2.24.0