From: Mel Gorman <mgorman@techsingularity.net>
To: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>,
Li Aubrey <aubrey.li@linux.intel.com>,
Qais Yousef <qais.yousef@arm.com>,
LKML <linux-kernel@vger.kernel.org>,
Mel Gorman <mgorman@techsingularity.net>
Subject: [PATCH 3/5] sched/fair: Make select_idle_cpu() proportional to cores
Date: Fri, 15 Jan 2021 10:08:53 +0000 [thread overview]
Message-ID: <20210115100855.23679-4-mgorman@techsingularity.net> (raw)
In-Reply-To: <20210115100855.23679-1-mgorman@techsingularity.net>
From: Peter Zijlstra (Intel) <peterz@infradead.org>
Instead of calculating how many (logical) CPUs to scan, compute how
many cores to scan.
This changes behaviour for anything !SMT2.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
---
kernel/sched/core.c | 18 +++++++++++++-----
kernel/sched/fair.c | 12 ++++++++++--
kernel/sched/sched.h | 2 ++
3 files changed, 25 insertions(+), 7 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 15d2562118d1..ada8faac2e4d 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7444,11 +7444,19 @@ int sched_cpu_activate(unsigned int cpu)
balance_push_set(cpu, false);
#ifdef CONFIG_SCHED_SMT
- /*
- * When going up, increment the number of cores with SMT present.
- */
- if (cpumask_weight(cpu_smt_mask(cpu)) == 2)
- static_branch_inc_cpuslocked(&sched_smt_present);
+ do {
+ int weight = cpumask_weight(cpu_smt_mask(cpu));
+
+ if (weight > sched_smt_weight)
+ sched_smt_weight = weight;
+
+ /*
+ * When going up, increment the number of cores with SMT present.
+ */
+ if (weight == 2)
+ static_branch_inc_cpuslocked(&sched_smt_present);
+
+ } while (0);
#endif
set_cpu_active(cpu, true);
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index c8d8e185cf3b..0811e2fe4f19 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6010,6 +6010,8 @@ static inline int find_idlest_cpu(struct sched_domain *sd, struct task_struct *p
DEFINE_STATIC_KEY_FALSE(sched_smt_present);
EXPORT_SYMBOL_GPL(sched_smt_present);
+int sched_smt_weight __read_mostly = 1;
+
static inline void set_idle_cores(int cpu, int val)
{
struct sched_domain_shared *sds;
@@ -6124,6 +6126,8 @@ static int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int t
#else /* CONFIG_SCHED_SMT */
+#define sched_smt_weight 1
+
static inline int select_idle_core(struct task_struct *p, struct sched_domain *sd, int target)
{
return -1;
@@ -6136,6 +6140,8 @@ static inline int select_idle_smt(struct task_struct *p, struct sched_domain *sd
#endif /* CONFIG_SCHED_SMT */
+#define sis_min_cores 2
+
/*
* Scan the LLC domain for idle CPUs; this is dynamically regulated by
* comparing the average scan cost (tracked in sd->avg_scan_cost) against the
@@ -6166,10 +6172,12 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t
avg_cost = this_sd->avg_scan_cost + 1;
span_avg = sd->span_weight * avg_idle;
- if (span_avg > 4*avg_cost)
+ if (span_avg > sis_min_cores*avg_cost)
nr = div_u64(span_avg, avg_cost);
else
- nr = 4;
+ nr = sis_min_cores;
+
+ nr *= sched_smt_weight;
time = cpu_clock(this);
}
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 12ada79d40f3..29aabe98dd1d 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1107,6 +1107,8 @@ static inline void update_idle_core(struct rq *rq)
__update_idle_core(rq);
}
+extern int sched_smt_weight;
+
#else
static inline void update_idle_core(struct rq *rq) { }
#endif
--
2.26.2
next prev parent reply other threads:[~2021-01-15 10:10 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-15 10:08 [PATCH v2 0/5] Scan for an idle sibling in a single pass Mel Gorman
2021-01-15 10:08 ` [PATCH 1/5] sched/fair: Remove SIS_AVG_CPU Mel Gorman
2021-01-15 10:08 ` [PATCH 2/5] sched/fair: Move avg_scan_cost calculations under SIS_PROP Mel Gorman
2021-01-15 10:08 ` Mel Gorman [this message]
2021-01-18 8:14 ` [PATCH 3/5] sched/fair: Make select_idle_cpu() proportional to cores Li, Aubrey
2021-01-18 9:27 ` Mel Gorman
2021-01-15 10:08 ` [PATCH 4/5] sched/fair: Remove select_idle_smt() Mel Gorman
2021-01-15 10:08 ` [PATCH 5/5] sched/fair: Merge select_idle_core/cpu() Mel Gorman
2021-01-18 12:55 ` Li, Aubrey
2021-01-18 14:41 ` Mel Gorman
-- strict thread matches above, loose matches on Subject: below --
2021-01-19 11:22 [PATCH v3 0/5] Scan for an idle sibling in a single pass Mel Gorman
2021-01-19 11:22 ` [PATCH 3/5] sched/fair: Make select_idle_cpu() proportional to cores Mel Gorman
2021-01-11 15:50 [PATCH 0/5] Scan for an idle sibling in a single pass Mel Gorman
2021-01-11 15:50 ` [PATCH 3/5] sched/fair: Make select_idle_cpu() proportional to cores Mel Gorman
2021-01-13 16:49 ` Vincent Guittot
2021-01-14 9:28 ` Mel Gorman
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