linux-kernel - [tip: sched/core] sched/balancing: Rename find_idlest_cpu() => sched_balance_find_dst

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Message-ID: <171024481845.398.6678071993830758312.tip-bot2@tip-bot2>
Date: Tue, 12 Mar 2024 12:00:18 -0000
From: "tip-bot2 for Ingo Molnar" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Ingo Molnar <mingo@...nel.org>, Shrikanth Hegde <sshegde@...ux.ibm.com>,
 x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: sched/core] sched/balancing: Rename find_idlest_cpu() =>
 sched_balance_find_dst_cpu()

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

Commit-ID:     686d148cbb5a1c2891914b8d11147d3c5556a29a
Gitweb:        https://git.kernel.org/tip/686d148cbb5a1c2891914b8d11147d3c5556a29a
Author:        Ingo Molnar <mingo@...nel.org>
AuthorDate:    Fri, 08 Mar 2024 12:18:19 +01:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Tue, 12 Mar 2024 12:00:00 +01:00

sched/balancing: Rename find_idlest_cpu() => sched_balance_find_dst_cpu()

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

Also use 'dst' instead of 'idlest', because it's not really
true 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@...nel.org>
Reviewed-by: Shrikanth Hegde <sshegde@...ux.ibm.com>
Link: https://lore.kernel.org/r/20240308111819.1101550-14-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 d0c3a09..4b3c4a1 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7160,7 +7160,7 @@ sched_balance_find_dst_group_cpu(struct sched_group *group, struct task_struct *
 	return shallowest_idle_cpu != -1 ? shallowest_idle_cpu : least_loaded_cpu;
 }
 
-static inline int find_idlest_cpu(struct sched_domain *sd, struct task_struct *p,
+static inline int sched_balance_find_dst_cpu(struct sched_domain *sd, struct task_struct *p,
 				  int cpu, int prev_cpu, int sd_flag)
 {
 	int new_cpu = cpu;
@@ -7936,7 +7936,7 @@ compute_energy(struct energy_env *eenv, struct perf_domain *pd,
  * NOTE: Forkees are not accepted in the energy-aware wake-up path because
  * they don't have any useful utilization data yet and it's not possible to
  * forecast their impact on energy consumption. Consequently, they will be
- * placed by find_idlest_cpu() on the least loaded CPU, which might turn out
+ * placed by sched_balance_find_dst_cpu() on the least loaded CPU, which might turn out
  * to be energy-inefficient in some use-cases. The alternative would be to
  * bias new tasks towards specific types of CPUs first, or to try to infer
  * their util_avg from the parent task, but those heuristics could hurt
@@ -8201,7 +8201,7 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int wake_flags)
 
 	if (unlikely(sd)) {
 		/* Slow path */
-		new_cpu = find_idlest_cpu(sd, p, cpu, prev_cpu, sd_flag);
+		new_cpu = sched_balance_find_dst_cpu(sd, p, cpu, prev_cpu, sd_flag);
 	} else if (wake_flags & WF_TTWU) { /* XXX always ? */
 		/* Fast path */
 		new_cpu = select_idle_sibling(p, prev_cpu, new_cpu);