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sched/core: Introduce 'struct sched_domain_shared' 

Since struct sched_domain is strictly per cpu; introduce a structure
that is shared between all 'identical' sched_domains.

Limit to SD_SHARE_PKG_RESOURCES domains for now, as we'll only use it
for shared cache state; if another use comes up later we can easily
relax this.

While the sched_group's are normally shared between CPUs, these are
not natural to use when we need some shared state on a domain level --
since that would require the domain to have a parent, which is not a
given.

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: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2016-05-09 10:37:59 +02:00 committed by Ingo Molnar
parent 16f3ef4680
commit 24fc7edb92
2 changed files with 45 additions and 5 deletions
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6
include/linux/sched.h
View File

@ -1067,6 +1067,10 @@ extern int sched_domain_level_max;
struct sched_group;
struct sched_domain_shared {
atomic_t ref;
};
struct sched_domain {
/* These fields must be setup */
struct sched_domain *parent; /* top domain must be null terminated */
@ -1135,6 +1139,7 @@ struct sched_domain {
void *private; /* used during construction */
struct rcu_head rcu; /* used during destruction */
};
struct sched_domain_shared *shared;
unsigned int span_weight;
/*
@ -1168,6 +1173,7 @@ typedef int (*sched_domain_flags_f)(void);
struct sd_data {
struct sched_domain **__percpu sd;
struct sched_domain_shared **__percpu sds;
struct sched_group **__percpu sg;
struct sched_group_capacity **__percpu sgc;
};

44
kernel/sched/core.c
View File

@ -5947,6 +5947,8 @@ static void destroy_sched_domain(struct sched_domain *sd)
kfree(sd->groups->sgc);
kfree(sd->groups);
}
if (sd->shared && atomic_dec_and_test(&sd->shared->ref))
kfree(sd->shared);
kfree(sd);
}
@ -6385,6 +6387,9 @@ static void claim_allocations(int cpu, struct sched_domain *sd)
WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
*per_cpu_ptr(sdd->sd, cpu) = NULL;
if (atomic_read(&(*per_cpu_ptr(sdd->sds, cpu))->ref))
*per_cpu_ptr(sdd->sds, cpu) = NULL;
if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
*per_cpu_ptr(sdd->sg, cpu) = NULL;
@ -6429,10 +6434,12 @@ static int sched_domains_curr_level;
static struct sched_domain *
sd_init(struct sched_domain_topology_level *tl,
const struct cpumask *cpu_map,
struct sched_domain *child, int cpu)
{
struct sched_domain *sd = *per_cpu_ptr(tl->data.sd, cpu);
int sd_weight, sd_flags = 0;
struct sd_data *sdd = &tl->data;
struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
int sd_id, sd_weight, sd_flags = 0;
#ifdef CONFIG_NUMA
/*
@ -6487,6 +6494,9 @@ sd_init(struct sched_domain_topology_level *tl,
#endif
};
cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu));
sd_id = cpumask_first(sched_domain_span(sd));
/*
* Convert topological properties into behaviour.
*/
@ -6529,7 +6539,16 @@ sd_init(struct sched_domain_topology_level *tl,
sd->idle_idx = 1;
}
sd->private = &tl->data;
/*
* For all levels sharing cache; connect a sched_domain_shared
* instance.
*/
if (sd->flags & SD_SHARE_PKG_RESOURCES) {
sd->shared = *per_cpu_ptr(sdd->sds, sd_id);
atomic_inc(&sd->shared->ref);
}
sd->private = sdd;
return sd;
}
@ -6839,6 +6858,10 @@ static int __sdt_alloc(const struct cpumask *cpu_map)
if (!sdd->sd)
return -ENOMEM;
sdd->sds = alloc_percpu(struct sched_domain_shared *);
if (!sdd->sds)
return -ENOMEM;
sdd->sg = alloc_percpu(struct sched_group *);
if (!sdd->sg)
return -ENOMEM;
@ -6849,6 +6872,7 @@ static int __sdt_alloc(const struct cpumask *cpu_map)
for_each_cpu(j, cpu_map) {
struct sched_domain *sd;
struct sched_domain_shared *sds;
struct sched_group *sg;
struct sched_group_capacity *sgc;
@ -6859,6 +6883,13 @@ static int __sdt_alloc(const struct cpumask *cpu_map)
*per_cpu_ptr(sdd->sd, j) = sd;
sds = kzalloc_node(sizeof(struct sched_domain_shared),
GFP_KERNEL, cpu_to_node(j));
if (!sds)
return -ENOMEM;
*per_cpu_ptr(sdd->sds, j) = sds;
sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
GFP_KERNEL, cpu_to_node(j));
if (!sg)
@ -6898,6 +6929,8 @@ static void __sdt_free(const struct cpumask *cpu_map)
kfree(*per_cpu_ptr(sdd->sd, j));
}
if (sdd->sds)
kfree(*per_cpu_ptr(sdd->sds, j));
if (sdd->sg)
kfree(*per_cpu_ptr(sdd->sg, j));
if (sdd->sgc)
@ -6905,6 +6938,8 @@ static void __sdt_free(const struct cpumask *cpu_map)
}
free_percpu(sdd->sd);
sdd->sd = NULL;
free_percpu(sdd->sds);
sdd->sds = NULL;
free_percpu(sdd->sg);
sdd->sg = NULL;
free_percpu(sdd->sgc);
@ -6916,9 +6951,8 @@ struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
const struct cpumask *cpu_map, struct sched_domain_attr *attr,
struct sched_domain *child, int cpu)
{
struct sched_domain *sd = sd_init(tl, child, cpu);
struct sched_domain *sd = sd_init(tl, cpu_map, child, cpu);
cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu));
if (child) {
sd->level = child->level + 1;
sched_domain_level_max = max(sched_domain_level_max, sd->level);