diff options
| -rw-r--r-- | kernel/cpuset.c | 123 |
1 files changed, 48 insertions, 75 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c index 5e348ae37ce9..0ddb48d40e4d 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -103,9 +103,6 @@ struct cpuset { /* for custom sched domain */ int relax_domain_level; - /* used for walking a cpuset hierarchy */ - struct list_head stack_list; - struct work_struct hotplug_work; }; @@ -207,6 +204,20 @@ static struct cpuset top_cpuset = { cgroup_for_each_child((pos_cgrp), (parent_cs)->css.cgroup) \ if (is_cpuset_online(((child_cs) = cgroup_cs((pos_cgrp))))) +/** + * cpuset_for_each_descendant_pre - pre-order walk of a cpuset's descendants + * @des_cs: loop cursor pointing to the current descendant + * @pos_cgrp: used for iteration + * @root_cs: target cpuset to walk ancestor of + * + * Walk @des_cs through the online descendants of @root_cs. Must be used + * with RCU read locked. The caller may modify @pos_cgrp by calling + * cgroup_rightmost_descendant() to skip subtree. + */ +#define cpuset_for_each_descendant_pre(des_cs, pos_cgrp, root_cs) \ + cgroup_for_each_descendant_pre((pos_cgrp), (root_cs)->css.cgroup) \ + if (is_cpuset_online(((des_cs) = cgroup_cs((pos_cgrp))))) + /* * There are two global mutexes guarding cpuset structures - cpuset_mutex * and callback_mutex. The latter may nest inside the former. We also @@ -507,31 +518,24 @@ update_domain_attr(struct sched_domain_attr *dattr, struct cpuset *c) return; } -static void -update_domain_attr_tree(struct sched_domain_attr *dattr, struct cpuset *c) +static void update_domain_attr_tree(struct sched_domain_attr *dattr, + struct cpuset *root_cs) { - LIST_HEAD(q); - - list_add(&c->stack_list, &q); - while (!list_empty(&q)) { - struct cpuset *cp; - struct cgroup *cont; - struct cpuset *child; - - cp = list_first_entry(&q, struct cpuset, stack_list); - list_del(q.next); + struct cpuset *cp; + struct cgroup *pos_cgrp; - if (cpumask_empty(cp->cpus_allowed)) + rcu_read_lock(); + cpuset_for_each_descendant_pre(cp, pos_cgrp, root_cs) { + /* skip the whole subtree if @cp doesn't have any CPU */ + if (cpumask_empty(cp->cpus_allowed)) { + pos_cgrp = cgroup_rightmost_descendant(pos_cgrp); continue; + } if (is_sched_load_balance(cp)) update_domain_attr(dattr, cp); - - rcu_read_lock(); - cpuset_for_each_child(child, cont, cp) - list_add_tail(&child->stack_list, &q); - rcu_read_unlock(); } + rcu_read_unlock(); } /* @@ -591,7 +595,6 @@ update_domain_attr_tree(struct sched_domain_attr *dattr, struct cpuset *c) static int generate_sched_domains(cpumask_var_t **domains, struct sched_domain_attr **attributes) { - LIST_HEAD(q); /* queue of cpusets to be scanned */ struct cpuset *cp; /* scans q */ struct cpuset **csa; /* array of all cpuset ptrs */ int csn; /* how many cpuset ptrs in csa so far */ @@ -600,6 +603,7 @@ static int generate_sched_domains(cpumask_var_t **domains, struct sched_domain_attr *dattr; /* attributes for custom domains */ int ndoms = 0; /* number of sched domains in result */ int nslot; /* next empty doms[] struct cpumask slot */ + struct cgroup *pos_cgrp; doms = NULL; dattr = NULL; @@ -627,33 +631,27 @@ static int generate_sched_domains(cpumask_var_t **domains, goto done; csn = 0; - list_add(&top_cpuset.stack_list, &q); - while (!list_empty(&q)) { - struct cgroup *cont; - struct cpuset *child; /* scans child cpusets of cp */ - - cp = list_first_entry(&q, struct cpuset, stack_list); - list_del(q.next); - - if (cpumask_empty(cp->cpus_allowed)) - continue; - + rcu_read_lock(); + cpuset_for_each_descendant_pre(cp, pos_cgrp, &top_cpuset) { /* - * All child cpusets contain a subset of the parent's cpus, so - * just skip them, and then we call update_domain_attr_tree() - * to calc relax_domain_level of the corresponding sched - * domain. + * Continue traversing beyond @cp iff @cp has some CPUs and + * isn't load balancing. The former is obvious. The + * latter: All child cpusets contain a subset of the + * parent's cpus, so just skip them, and then we call + * update_domain_attr_tree() to calc relax_domain_level of + * the corresponding sched domain. */ - if (is_sched_load_balance(cp)) { - csa[csn++] = cp; + if (!cpumask_empty(cp->cpus_allowed) && + !is_sched_load_balance(cp)) continue; - } - rcu_read_lock(); - cpuset_for_each_child(child, cont, cp) - list_add_tail(&child->stack_list, &q); - rcu_read_unlock(); - } + if (is_sched_load_balance(cp)) + csa[csn++] = cp; + + /* skip @cp's subtree */ + pos_cgrp = cgroup_rightmost_descendant(pos_cgrp); + } + rcu_read_unlock(); for (i = 0; i < csn; i++) csa[i]->pn = i; @@ -2068,31 +2066,6 @@ static void remove_tasks_in_empty_cpuset(struct cpuset *cs) move_member_tasks_to_cpuset(cs, parent); } -/* - * Helper function to traverse cpusets. - * It can be used to walk the cpuset tree from top to bottom, completing - * one layer before dropping down to the next (thus always processing a - * node before any of its children). - */ -static struct cpuset *cpuset_next(struct list_head *queue) -{ - struct cpuset *cp; - struct cpuset *child; /* scans child cpusets of cp */ - struct cgroup *cont; - - if (list_empty(queue)) - return NULL; - - cp = list_first_entry(queue, struct cpuset, stack_list); - list_del(queue->next); - rcu_read_lock(); - cpuset_for_each_child(child, cont, cp) - list_add_tail(&child->stack_list, queue); - rcu_read_unlock(); - - return cp; -} - /** * cpuset_propagate_hotplug_workfn - propagate CPU/memory hotplug to a cpuset * @cs: cpuset in interest @@ -2229,12 +2202,12 @@ static void cpuset_hotplug_workfn(struct work_struct *work) /* if cpus or mems went down, we need to propagate to descendants */ if (cpus_offlined || mems_offlined) { struct cpuset *cs; - LIST_HEAD(queue); + struct cgroup *pos_cgrp; - list_add_tail(&top_cpuset.stack_list, &queue); - while ((cs = cpuset_next(&queue))) - if (cs != &top_cpuset) - schedule_cpuset_propagate_hotplug(cs); + rcu_read_lock(); + cpuset_for_each_descendant_pre(cs, pos_cgrp, &top_cpuset) + schedule_cpuset_propagate_hotplug(cs); + rcu_read_unlock(); } mutex_unlock(&cpuset_mutex); |