linux-kernel - [PATCH 4/5] sched/fair: Remove select_idle

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Date:   Fri, 15 Jan 2021 10:08:54 +0000
From:   Mel Gorman <mgorman@...hsingularity.net>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>
Cc:     Vincent Guittot <vincent.guittot@...aro.org>,
        Li Aubrey <aubrey.li@...ux.intel.com>,
        Qais Yousef <qais.yousef@....com>,
        LKML <linux-kernel@...r.kernel.org>,
        Mel Gorman <mgorman@...hsingularity.net>
Subject: [PATCH 4/5] sched/fair: Remove select_idle_smt()

From: Peter Zijlstra (Intel) <peterz@...radead.org>

In order to make the next patch more readable, and to quantify the
actual effectiveness of this pass, start by removing it.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Mel Gorman <mgorman@...hsingularity.net>
---
 kernel/sched/fair.c | 30 ------------------------------
 1 file changed, 30 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 0811e2fe4f19..12e08da90024 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6103,27 +6103,6 @@ static int select_idle_core(struct task_struct *p, struct sched_domain *sd, int
 	return -1;
 }
 
-/*
- * Scan the local SMT mask for idle CPUs.
- */
-static int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target)
-{
-	int cpu;
-
-	if (!static_branch_likely(&sched_smt_present))
-		return -1;
-
-	for_each_cpu(cpu, cpu_smt_mask(target)) {
-		if (!cpumask_test_cpu(cpu, p->cpus_ptr) ||
-		    !cpumask_test_cpu(cpu, sched_domain_span(sd)))
-			continue;
-		if (available_idle_cpu(cpu) || sched_idle_cpu(cpu))
-			return cpu;
-	}
-
-	return -1;
-}
-
 #else /* CONFIG_SCHED_SMT */
 
 #define sched_smt_weight	1
@@ -6133,11 +6112,6 @@ static inline int select_idle_core(struct task_struct *p, struct sched_domain *s
 	return -1;
 }
 
-static inline int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target)
-{
-	return -1;
-}
-
 #endif /* CONFIG_SCHED_SMT */
 
 #define sis_min_cores		2
@@ -6331,10 +6305,6 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target)
 	if ((unsigned)i < nr_cpumask_bits)
 		return i;
 
-	i = select_idle_smt(p, sd, target);
-	if ((unsigned)i < nr_cpumask_bits)
-		return i;
-
 	return target;
 }
 
-- 
2.26.2