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From: Peter Zijlstra <peterz@infradead.org>
To: mingo@kernel.org, linux-kernel@vger.kernel.org
Cc: subhra.mazumdar@oracle.com, steven.sistare@oracle.com,
	dhaval.giani@oracle.com, rohit.k.jain@oracle.com,
	umgwanakikbuti@gmail.com, matt@codeblueprint.co.uk,
	riel@surriel.com, peterz@infradead.org
Subject: [RFC 11/11] sched/fair: Remove SIS_FOLD
Date: Wed, 30 May 2018 16:22:47 +0200	[thread overview]
Message-ID: <20180530143106.448422984@infradead.org> (raw)
In-Reply-To: <20180530142236.667774973@infradead.org>

[-- Attachment #1: peterz-sis-again-8.patch --]
[-- Type: text/plain, Size: 3708 bytes --]

Since the new code works, remove the old.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 kernel/sched/fair.c     |   90 +-----------------------------------------------
 kernel/sched/features.h |    4 +-
 2 files changed, 4 insertions(+), 90 deletions(-)

--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6291,65 +6291,6 @@ void __update_idle_core(struct rq *rq)
 	rcu_read_unlock();
 }
 
-/*
- * Scan the entire LLC domain for idle cores; this dynamically switches off if
- * there are no idle cores left in the system; tracked through
- * sd_llc->shared->has_idle_cores and enabled through update_idle_core() above.
- */
-static int select_idle_core(struct task_struct *p, struct sched_domain *sd, int target)
-{
-	struct cpumask *cpus = this_cpu_cpumask_var_ptr(select_idle_mask);
-	int core, cpu;
-
-	if (!static_branch_likely(&sched_smt_present))
-		return -1;
-
-	if (!test_idle_cores(target, false))
-		return -1;
-
-	cpumask_and(cpus, sched_domain_span(sd), &p->cpus_allowed);
-
-	for_each_cpu_wrap(core, cpus, target) {
-		bool idle = true;
-
-		for_each_cpu(cpu, cpu_smt_mask(core)) {
-			cpumask_clear_cpu(cpu, cpus);
-			if (!available_idle_cpu(cpu))
-				idle = false;
-		}
-
-		if (idle)
-			return core;
-	}
-
-	/*
-	 * Failed to find an idle core; stop looking for one.
-	 */
-	set_idle_cores(target, 0);
-
-	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_allowed))
-			continue;
-		if (available_idle_cpu(cpu))
-			return cpu;
-	}
-
-	return -1;
-}
-
 static int __select_idle_core(struct task_struct *p, struct sched_domain *sd,
 			      int target, int nr, int *ploops)
 {
@@ -6391,16 +6332,6 @@ static int __select_idle_core(struct tas
 
 #define sched_smt_weight	1
 
-static inline int select_idle_core(struct task_struct *p, struct sched_domain *sd, int target)
-{
-	return -1;
-}
-
-static inline int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target)
-{
-	return -1;
-}
-
 #endif /* CONFIG_SCHED_SMT */
 
 static int __select_idle_cpu(struct task_struct *p, struct sched_domain *sd,
@@ -6470,8 +6401,7 @@ static int select_idle_cpu(struct task_s
 	}
 
 #ifdef CONFIG_SCHED_SMT
-	if (sched_feat(SIS_FOLD) && static_branch_likely(&sched_smt_present) &&
-	    test_idle_cores(target, false))
+	if (static_branch_likely(&sched_smt_present) && test_idle_cores(target, false))
 		cpu = __select_idle_core(p, sd, target, nr, &loops);
 	else
 #endif
@@ -6536,25 +6466,9 @@ static int select_idle_sibling(struct ta
 	if (!sd)
 		return target;
 
-	if (sched_feat(SIS_FOLD)) {
-		i = select_idle_cpu(p, sd, target);
-		if ((unsigned)i < nr_cpumask_bits)
-			target = i;
-
-		return target;
-	}
-
-	i = select_idle_core(p, sd, target);
-	if ((unsigned)i < nr_cpumask_bits)
-		return i;
-
 	i = select_idle_cpu(p, sd, target);
 	if ((unsigned)i < nr_cpumask_bits)
-		return i;
-
-	i = select_idle_smt(p, sd, target);
-	if ((unsigned)i < nr_cpumask_bits)
-		return i;
+		target = i;
 
 	return target;
 }
--- a/kernel/sched/features.h
+++ b/kernel/sched/features.h
@@ -53,10 +53,10 @@ SCHED_FEAT(NONTASK_CAPACITY, true)
 SCHED_FEAT(TTWU_QUEUE, true)
 
 /*
- * When doing wakeups, attempt to limit superfluous scans of the LLC domain.
+ * When doing wakeups, attempt to limit scanning cost of the LLC proportional
+ * to the average idle time.
  */
 SCHED_FEAT(SIS_PROP, true)
-SCHED_FEAT(SIS_FOLD, true)
 
 /*
  * Issue a WARN when we do multiple update_rq_clock() calls

  parent reply	other threads:[~2018-05-30 14:39 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-30 14:22 [RFC 00/11] select_idle_sibling rework Peter Zijlstra
2018-05-30 14:22 ` [RFC 01/11] sched/fair: Fix select_idle_cpu()s cost accounting Peter Zijlstra
2018-05-30 14:22 ` [RFC 02/11] sched/fair: Age the average idle time Peter Zijlstra
2018-05-30 14:22 ` [RFC 03/11] sched/fair: Only use time once Peter Zijlstra
2018-05-30 14:22 ` [RFC 04/11] sched/topology: Introduce sched_domain_cores() Peter Zijlstra
2018-05-30 14:22 ` [RFC 05/11] sched/fair: Re-arrange select_idle_cpu() Peter Zijlstra
2018-05-30 14:22 ` [RFC 06/11] sched/fair: Make select_idle_cpu() proportional to cores Peter Zijlstra
2018-05-30 14:22 ` [RFC 07/11] sched/fair: Fold the select_idle_sibling() scans Peter Zijlstra
2018-05-30 14:22 ` [RFC 08/11] sched/fair: Optimize SIS_FOLD Peter Zijlstra
2018-05-30 14:22 ` [RFC 09/11] sched/fair: Remove SIS_AVG_PROP Peter Zijlstra
2018-05-30 14:22 ` [RFC 10/11] sched/fair: Remove SIS_AGE/SIS_ONCE Peter Zijlstra
2018-05-30 14:22 ` Peter Zijlstra [this message]
2018-06-19 22:06 ` [RFC 00/11] select_idle_sibling rework Matt Fleming
2018-06-20 22:20   ` Steven Sistare

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