sched/balancing: Standardize the naming of scheduler load-balancing functions

[PATCH 11/13] sched/balancing: Rename find_idlest_group_cpu() => sched_balance_find_dst_group_cpu()

Posted by Ingo Molnar 1 year, 11 months ago

Standardize scheduler load-balancing function names on the
sched_balance_() prefix.

Also use 'dst' instead of 'idlest': while historically correct,
today it's not really true anymore that we return the 'idlest'
group or CPU, we sort by idle-exit latency and only return the
idlest CPUs from the lowest-latency set of CPUs.

The true 'idlest' CPUs often remain idle for a long time
and are never returned as long as the system is under-loaded.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
---
 kernel/sched/fair.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index aa5ff0efcca8..02ff0272b2e4 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7101,10 +7101,10 @@ static struct sched_group *
 find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu);
 
 /*
- * find_idlest_group_cpu - find the idlest CPU among the CPUs in the group.
+ * sched_balance_find_dst_group_cpu - find the idlest CPU among the CPUs in the group.
  */
 static int
-find_idlest_group_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
+sched_balance_find_dst_group_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
 {
 	unsigned long load, min_load = ULONG_MAX;
 	unsigned int min_exit_latency = UINT_MAX;
@@ -7191,7 +7191,7 @@ static inline int find_idlest_cpu(struct sched_domain *sd, struct task_struct *p
 			continue;
 		}
 
-		new_cpu = find_idlest_group_cpu(group, p, cpu);
+		new_cpu = sched_balance_find_dst_group_cpu(group, p, cpu);
 		if (new_cpu == cpu) {
 			/* Now try balancing at a lower domain level of 'cpu': */
 			sd = sd->child;
-- 
2.40.1

[tip: sched/core] sched/balancing: Rename find_idlest_group_cpu() => sched_balance_find_dst_group_cpu()

Posted by tip-bot2 for Ingo Molnar 1 year, 11 months ago

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     646ebaf51c64c6416ca89765c20041363fc1b518
Gitweb:        https://git.kernel.org/tip/646ebaf51c64c6416ca89765c20041363fc1b518
Author:        Ingo Molnar <mingo@kernel.org>
AuthorDate:    Fri, 08 Mar 2024 12:18:17 +01:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Tue, 12 Mar 2024 12:00:00 +01:00

sched/balancing: Rename find_idlest_group_cpu() => sched_balance_find_dst_group_cpu()

Standardize scheduler load-balancing function names on the
sched_balance_() prefix.

Also use 'dst' instead of 'idlest': while historically correct,
today it's not really true anymore that we return the 'idlest'
group or CPU, we sort by idle-exit latency and only return the
idlest CPUs from the lowest-latency set of CPUs.

The true 'idlest' CPUs often remain idle for a long time
and are never returned as long as the system is under-loaded.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://lore.kernel.org/r/20240308111819.1101550-12-mingo@kernel.org
---
 kernel/sched/fair.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index aa5ff0e..02ff027 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7101,10 +7101,10 @@ static struct sched_group *
 find_idlest_group(struct sched_domain *sd, struct task_struct *p, int this_cpu);
 
 /*
- * find_idlest_group_cpu - find the idlest CPU among the CPUs in the group.
+ * sched_balance_find_dst_group_cpu - find the idlest CPU among the CPUs in the group.
  */
 static int
-find_idlest_group_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
+sched_balance_find_dst_group_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
 {
 	unsigned long load, min_load = ULONG_MAX;
 	unsigned int min_exit_latency = UINT_MAX;
@@ -7191,7 +7191,7 @@ static inline int find_idlest_cpu(struct sched_domain *sd, struct task_struct *p
 			continue;
 		}
 
-		new_cpu = find_idlest_group_cpu(group, p, cpu);
+		new_cpu = sched_balance_find_dst_group_cpu(group, p, cpu);
 		if (new_cpu == cpu) {
 			/* Now try balancing at a lower domain level of 'cpu': */
 			sd = sd->child;