Messages in this thread Patch in this message | | | Date | Thu, 18 Aug 2016 03:58:16 -0700 | From | tip-bot for Dietmar Eggemann <> | Subject | [tip:sched/core] sched/core: Store maximum per-CPU capacity in root domain |
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Commit-ID: cd92bfd3b8cb0ec2ee825e55a3aee704cd55aea9 Gitweb: http://git.kernel.org/tip/cd92bfd3b8cb0ec2ee825e55a3aee704cd55aea9 Author: Dietmar Eggemann <dietmar.eggemann@arm.com> AuthorDate: Mon, 1 Aug 2016 19:53:35 +0100 Committer: Ingo Molnar <mingo@kernel.org> CommitDate: Thu, 18 Aug 2016 11:26:55 +0200
sched/core: Store maximum per-CPU capacity in root domain
To be able to compare the capacity of the target CPU with the highest available CPU capacity, store the maximum per-CPU capacity in the root domain.
The max per-CPU capacity should be 1024 for all systems except SMT, where the capacity is currently based on smt_gain and the number of hardware threads and is <1024. If SMT can be brought to work with a per-thread capacity of 1024, this patch can be dropped and replaced by a hard-coded max capacity of 1024 (=SCHED_CAPACITY_SCALE).
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: freedom.tan@mediatek.com Cc: keita.kobayashi.ym@renesas.com Cc: mgalbraith@suse.de Cc: sgurrappadi@nvidia.com Cc: vincent.guittot@linaro.org Cc: yuyang.du@intel.com Link: http://lkml.kernel.org/r/26c69258-9947-f830-a53e-0c54e7750646@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org> --- kernel/sched/core.c | 12 ++++++++++++ kernel/sched/sched.h | 2 ++ 2 files changed, 14 insertions(+)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 4695df6..6924314 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6903,6 +6903,7 @@ static int build_sched_domains(const struct cpumask *cpu_map, enum s_alloc alloc_state; struct sched_domain *sd; struct s_data d; + struct rq *rq = NULL; int i, ret = -ENOMEM; alloc_state = __visit_domain_allocation_hell(&d, cpu_map); @@ -6953,11 +6954,22 @@ static int build_sched_domains(const struct cpumask *cpu_map, /* Attach the domains */ rcu_read_lock(); for_each_cpu(i, cpu_map) { + rq = cpu_rq(i); sd = *per_cpu_ptr(d.sd, i); + + /* Use READ_ONCE()/WRITE_ONCE() to avoid load/store tearing: */ + if (rq->cpu_capacity_orig > READ_ONCE(d.rd->max_cpu_capacity)) + WRITE_ONCE(d.rd->max_cpu_capacity, rq->cpu_capacity_orig); + cpu_attach_domain(sd, d.rd, i); } rcu_read_unlock(); + if (rq) { + pr_info("span: %*pbl (max cpu_capacity = %lu)\n", + cpumask_pr_args(cpu_map), rq->rd->max_cpu_capacity); + } + ret = 0; error: __free_domain_allocs(&d, alloc_state, cpu_map); diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index afe76d0..420c05d 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -565,6 +565,8 @@ struct root_domain { */ cpumask_var_t rto_mask; struct cpupri cpupri; + + unsigned long max_cpu_capacity; }; extern struct root_domain def_root_domain;
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