| Message ID | 26c69258-9947-f830-a53e-0c54e7750646@arm.com |
|---|---|
| State | New |
| Headers | show |
On 1 August 2016 at 20:53, Dietmar Eggemann <dietmar.eggemann@arm.com> wrote: > On 25/07/16 14:34, Morten Rasmussen wrote: > > [...] > >> @@ -6923,11 +6924,22 @@ 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(rq->rd->max_cpu_capacity)) >> + WRITE_ONCE(rq->rd->max_cpu_capacity, rq->cpu_capacity_orig); > > We have to use d.rd rather rq->rd here since from v3 on we have this if > condition in front of the cpu_attach_domain() call which replaces > rq->rd with d.rd. Fixed patch below. > >> + >> 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); > > [...] > > -- >8 -- > > From: Dietmar Eggemann <dietmar.eggemann@arm.com> > > 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). FWIW, Acked-by: Vincent Guittot <vincent.guittot@linaro.org> > > cc: Ingo Molnar <mingo@redhat.com> > cc: Peter Zijlstra <peterz@infradead.org> > > Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com> > Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com> > --- > 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 a0a74b2d9f41..db03e6226d54 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -6873,6 +6873,7 @@ 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); > @@ -6923,11 +6924,22 @@ 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 f44da95c70cd..444d8f38743f 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; > -- > 1.9.1
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index a0a74b2d9f41..db03e6226d54 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6873,6 +6873,7 @@ 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); @@ -6923,11 +6924,22 @@ 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 f44da95c70cd..444d8f38743f 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;