linux-kernel - [PATCH v2 3/6] sched/deadline: Add dl_bw

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Date:   Mon, 27 Apr 2020 10:37:06 +0200
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>
Cc:     Vincent Guittot <vincent.guittot@...aro.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Luca Abeni <luca.abeni@...tannapisa.it>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Wei Wang <wvw@...gle.com>, Quentin Perret <qperret@...gle.com>,
        Alessio Balsini <balsini@...gle.com>,
        Pavan Kondeti <pkondeti@...eaurora.org>,
        Patrick Bellasi <patrick.bellasi@...bug.net>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Valentin Schneider <valentin.schneider@....com>,
        Qais Yousef <qais.yousef@....com>, linux-kernel@...r.kernel.org
Subject: [PATCH v2 3/6] sched/deadline: Add dl_bw_capacity()

Capacity-aware SCHED_DEADLINE admission control needs rd (root domain)
CPU capacity sum.

The design of this function follows that of dl_bw_cpus().

That is, return the rd CPU capacity sum in case the rd span a subset of
the cpu_active_mask.

Compute the CPU capacity sum over rd span and cpu_active_mask when in
hotplug.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@....com>
---
 kernel/sched/deadline.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 4ae22bfc37ae..eb23e6921d94 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -69,6 +69,25 @@ static inline int dl_bw_cpus(int i)
 
 	return cpus;
 }
+
+static inline unsigned long dl_bw_capacity(int i)
+{
+	struct root_domain *rd = cpu_rq(i)->rd;
+	unsigned long cap;
+
+	RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(),
+			 "sched RCU must be held");
+
+	if (cpumask_subset(rd->span, cpu_active_mask))
+		return rd->sum_cpu_capacity;
+
+	cap = 0;
+
+	for_each_cpu_and(i, rd->span, cpu_active_mask)
+		cap += capacity_orig_of(i);
+
+	return cap;
+}
 #else
 static inline struct dl_bw *dl_bw_of(int i)
 {
@@ -79,6 +98,11 @@ static inline int dl_bw_cpus(int i)
 {
 	return 1;
 }
+
+static inline unsigned long dl_bw_capacity(int i)
+{
+	return SCHED_CAPACITY_SCALE;
+}
 #endif
 
 static inline
-- 
2.17.1