Commit fc9dc698 authored by Dietmar Eggemann's avatar Dietmar Eggemann Committed by Peter Zijlstra

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: default avatarDietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarJuri Lelli <juri.lelli@redhat.com>
Link: https://lkml.kernel.org/r/20200520134243.19352-3-dietmar.eggemann@arm.com
parent c81b8932
......@@ -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
......
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