From: Peter Zijlstra <peterz@infradead.org>
To: mgorman@techsingularity.net, vincent.guittot@linaro.org
Cc: peterz@infradead.org, linux-kernel@vger.kernel.org,
aubrey.li@linux.intel.com, mingo@redhat.com,
juri.lelli@redhat.com, valentin.schneider@arm.com,
qais.yousef@arm.com, dietmar.eggemann@arm.com,
rostedt@goodmis.org, bsegall@google.com,
tim.c.chen@linux.intel.com, benbjiang@gmail.com
Subject: [RFC][PATCH 2/5] sched/fair: Make select_idle_cpu() proportional to cores
Date: Mon, 14 Dec 2020 17:48:24 +0100 [thread overview]
Message-ID: <20201214170017.938791025@infradead.org> (raw)
In-Reply-To: 20201214164822.402812729@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>
---
kernel/sched/core.c | 19 ++++++++++++++-----
kernel/sched/fair.c | 12 ++++++++++--
2 files changed, 24 insertions(+), 7 deletions(-)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7454,11 +7454,20 @@ 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));
+ extern int sched_smt_weight;
+
+ 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);
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6010,6 +6010,8 @@ static inline int find_idlest_cpu(struct
DEFINE_STATIC_KEY_FALSE(sched_smt_present);
EXPORT_SYMBOL_GPL(sched_smt_present);
+int sched_smt_weight = 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_s
#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
#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_s
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);
}
next prev parent reply other threads:[~2020-12-14 17:13 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-14 16:48 [RFC][PATCH 0/5] select_idle_sibling() wreckage Peter Zijlstra
2020-12-14 16:48 ` [RFC][PATCH 1/5] sched/fair: Fix select_idle_cpu()s cost accounting Peter Zijlstra
2020-12-15 3:36 ` Li, Aubrey
2020-12-15 7:59 ` Peter Zijlstra
2020-12-15 11:45 ` Mel Gorman
2020-12-15 12:13 ` Li, Aubrey
2021-01-08 10:27 ` Mel Gorman
2021-01-08 13:01 ` Qais Yousef
2021-01-08 13:47 ` Mel Gorman
2021-01-08 13:41 ` Vincent Guittot
2021-01-08 14:40 ` Mel Gorman
2021-01-08 15:10 ` Vincent Guittot
2021-01-08 16:14 ` Mel Gorman
2021-01-11 14:36 ` Vincent Guittot
2021-01-11 15:58 ` Mel Gorman
2021-01-08 19:45 ` Peter Zijlstra
2021-01-09 14:12 ` Mel Gorman
2021-01-11 14:39 ` Vincent Guittot
2021-01-08 19:49 ` Peter Zijlstra
2021-01-11 14:52 ` Vincent Guittot
2021-01-08 20:21 ` Peter Zijlstra
2021-01-09 13:59 ` Mel Gorman
2020-12-14 16:48 ` Peter Zijlstra [this message]
2020-12-23 13:31 ` [RFC][PATCH 2/5] sched/fair: Make select_idle_cpu() proportional to cores Vincent Guittot
2020-12-14 16:48 ` [RFC][PATCH 3/5] sched/fair: Remove select_idle_smt() Peter Zijlstra
2020-12-14 16:48 ` [RFC][PATCH 4/5] sched/fair: Merge select_idle_core/cpu() Peter Zijlstra
2020-12-14 16:48 ` [RFC][PATCH 5/5] sched/fair: SIS_PROP the idle core scan Peter Zijlstra
2020-12-16 12:59 ` [RFC][PATCH 0/5] select_idle_sibling() wreckage Li, Aubrey
2020-12-16 18:07 ` Vincent Guittot
2020-12-23 13:23 ` Vincent Guittot
2021-01-04 15:40 ` Mel Gorman
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