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Date: Wed, 20 May 2020 15:42:40 +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 v3 2/5] 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 <dietmar.eggemann@....com> --- kernel/sched/deadline.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 4ae22bfc37ae..ea7282ce484c 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 -- 2.17.1
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