From: Juri Lelli <juri.lelli@redhat.com>
To: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
Steven Rostedt <rostedt@goodmis.org>,
Luca Abeni <luca.abeni@santannapisa.it>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Wei Wang <wvw@google.com>, Quentin Perret <qperret@google.com>,
Alessio Balsini <balsini@google.com>,
Pavan Kondeti <pkondeti@codeaurora.org>,
Patrick Bellasi <patrick.bellasi@matbug.net>,
Morten Rasmussen <morten.rasmussen@arm.com>,
Valentin Schneider <valentin.schneider@arm.com>,
Qais Yousef <qais.yousef@arm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 2/5] sched/deadline: Add dl_bw_capacity()
Date: Fri, 22 May 2020 16:58:02 +0200 [thread overview]
Message-ID: <20200522145802.GC600689@localhost.localdomain> (raw)
In-Reply-To: <20200520134243.19352-3-dietmar.eggemann@arm.com>
On 20/05/20 15:42, Dietmar Eggemann wrote:
> 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@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 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
> --
Acked-by: Juri Lelli <juri.lelli@redhat.com>
next prev parent reply other threads:[~2020-05-22 14:58 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-20 13:42 [PATCH v3 0/5] Capacity awareness for SCHED_DEADLINE Dietmar Eggemann
2020-05-20 13:42 ` [PATCH v3 1/5] sched/deadline: Optimize dl_bw_cpus() Dietmar Eggemann
2020-05-22 14:57 ` Juri Lelli
2020-06-16 12:21 ` [tip: sched/core] " tip-bot2 for Dietmar Eggemann
2020-05-20 13:42 ` [PATCH v3 2/5] sched/deadline: Add dl_bw_capacity() Dietmar Eggemann
2020-05-22 14:58 ` Juri Lelli [this message]
2020-06-16 12:21 ` [tip: sched/core] " tip-bot2 for Dietmar Eggemann
2020-05-20 13:42 ` [PATCH v3 3/5] sched/deadline: Improve admission control for asymmetric CPU capacities Dietmar Eggemann
2020-05-22 14:58 ` Juri Lelli
2020-06-16 12:21 ` [tip: sched/core] " tip-bot2 for Luca Abeni
2020-05-20 13:42 ` [PATCH v3 4/5] sched/deadline: Make DL capacity-aware Dietmar Eggemann
2020-05-22 14:58 ` Juri Lelli
2020-06-16 12:21 ` [tip: sched/core] " tip-bot2 for Luca Abeni
2020-05-20 13:42 ` [PATCH v3 5/5] sched/deadline: Implement fallback mechanism for !fit case Dietmar Eggemann
2020-05-22 14:59 ` Juri Lelli
2020-06-16 12:21 ` [tip: sched/core] " tip-bot2 for Luca Abeni
2020-06-10 10:26 ` [PATCH v3 0/5] Capacity awareness for SCHED_DEADLINE Peter Zijlstra
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