From fc9dc698472aa460a8b3b036d9b1d0b751f12f58 Mon Sep 17 00:00:00 2001 From: Dietmar Eggemann Date: Wed, 20 May 2020 15:42:40 +0200 Subject: sched/deadline: Add dl_bw_capacity() Capacity-aware SCHED_DEADLINE Admission Control (AC) needs root domain (rd) CPU capacity sum. Introduce dl_bw_capacity() which for a symmetric rd w/ a CPU capacity of SCHED_CAPACITY_SCALE simply relies on dl_bw_cpus() to return #CPUs multiplied by SCHED_CAPACITY_SCALE. For an asymmetric rd or a CPU capacity < SCHED_CAPACITY_SCALE it computes the CPU capacity sum over rd span and cpu_active_mask. A 'XXX Fix:' comment was added to highlight that if 'rq->rd == def_root_domain' AC should be performed against the capacity of the CPU the task is running on rather the rd CPU capacity sum. This issue already exists w/o capacity awareness. Signed-off-by: Dietmar Eggemann Signed-off-by: Peter Zijlstra (Intel) Acked-by: Juri Lelli Link: https://lkml.kernel.org/r/20200520134243.19352-3-dietmar.eggemann@arm.com --- kernel/sched/deadline.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index ec90265e9d8e..01f474a5bd14 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -69,6 +69,34 @@ 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 = 0; + + RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(), + "sched RCU must be held"); + + for_each_cpu_and(i, rd->span, cpu_active_mask) + cap += capacity_orig_of(i); + + return cap; +} + +/* + * XXX Fix: If 'rq->rd == def_root_domain' perform AC against capacity + * of the CPU the task is running on rather rd's \Sum CPU capacity. + */ +static inline unsigned long dl_bw_capacity(int i) +{ + if (!static_branch_unlikely(&sched_asym_cpucapacity) && + capacity_orig_of(i) == SCHED_CAPACITY_SCALE) { + return dl_bw_cpus(i) << SCHED_CAPACITY_SHIFT; + } else { + return __dl_bw_capacity(i); + } +} #else static inline struct dl_bw *dl_bw_of(int i) { @@ -79,6 +107,11 @@ 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 -- cgit v1.2.3