The creation of a cpuset partition means dedicating a set of exclusive CPUs to be used by a particular partition only. These exclusive CPUs will not be used by any cpusets outside of that partition.
To enable more flexibility in creating partitions, we need a way to distribute exclusive CPUs that can be used in new partitions. Currently, we have a subparts_cpus cpumask in struct cpuset that tracks only the exclusive CPUs used by all the sub-partitions underneath a given cpuset. This patch reworks the way we do exclusive CPUs tracking. The subparts_cpus is now renamed to exclusive_cpus which tracks the exclusive CPUs allocated to a partition root including those that are further distributed down to sub-partitions underneath it. IOW, it also includes the exclusive CPUs used by the current partition root.
The renamed exclusive_cpus is now exposed via a new read-only "cpuset.cpus.exclusive" control file. The new exclusive_cpus cpumask will be set to cpus_allowed when a cpuset becomes a partition root and cleared if it is not a valid partition root.
In the next patch, we will enable write to this new control file and allow it to differ from cpus_allowed. However, it must remains a subset of cpus_allowed.
A parent cpuset can distribute an exclusive CPU to at most one of its children only.
Signed-off-by: Waiman Long longman@redhat.com --- kernel/cgroup/cpuset.c | 733 ++++++++++++++++++++++++----------------- 1 file changed, 428 insertions(+), 305 deletions(-)
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 64f9e305b3ab..9f2ec8394736 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -78,7 +78,7 @@ enum prs_errcode { };
static const char * const perr_strings[] = { - [PERR_INVCPUS] = "Invalid cpu list in cpuset.cpus", + [PERR_INVCPUS] = "Invalid cpu list in cpuset.cpus.exclusive", [PERR_INVPARENT] = "Parent is an invalid partition root", [PERR_NOTPART] = "Parent is not a partition root", [PERR_NOTEXCL] = "Cpu list in cpuset.cpus not exclusive", @@ -121,14 +121,18 @@ struct cpuset { nodemask_t effective_mems;
/* - * CPUs allocated to child sub-partitions (default hierarchy only) - * - CPUs granted by the parent = effective_cpus U subparts_cpus - * - effective_cpus and subparts_cpus are mutually exclusive. + * Exclusive CPUs dedicated to current cgroup (default hierarchy only) * - * effective_cpus contains only onlined CPUs, but subparts_cpus - * may have offlined ones. + * This exclusive CPUs must be a subset of cpus_allowed. A parent + * cgroup can only grant exclusive CPUs to one of its children. + * + * When the cgroup becomes a valid partition root, exclusive_cpus + * defaults to cpus_allowed if not set. The effective_cpus of a valid + * partition root comes solely from its exclusive_cpus and some of the + * exclusive_cpus may be distributed to sub-partitions below & hence + * excluded from its effective_cpus. */ - cpumask_var_t subparts_cpus; + cpumask_var_t exclusive_cpus;
/* * This is old Memory Nodes tasks took on. @@ -156,8 +160,8 @@ struct cpuset { /* for custom sched domain */ int relax_domain_level;
- /* number of CPUs in subparts_cpus */ - int nr_subparts_cpus; + /* number of valid sub-partitions */ + int nr_subparts;
/* partition root state */ int partition_root_state; @@ -185,6 +189,11 @@ struct cpuset { struct cgroup_file partition_file; };
+/* + * Exclusive CPUs distributed out to sub-partitions of top_cpuset + */ +static cpumask_var_t subpartitions_cpus; + /* * Partition root states: * @@ -312,7 +321,7 @@ static inline int is_partition_invalid(const struct cpuset *cs) */ static inline void make_partition_invalid(struct cpuset *cs) { - if (is_partition_valid(cs)) + if (cs->partition_root_state > 0) cs->partition_root_state = -cs->partition_root_state; }
@@ -469,7 +478,7 @@ static inline bool partition_is_populated(struct cpuset *cs,
if (cs->css.cgroup->nr_populated_csets) return true; - if (!excluded_child && !cs->nr_subparts_cpus) + if (!excluded_child && !cs->nr_subparts) return cgroup_is_populated(cs->css.cgroup);
rcu_read_lock(); @@ -601,7 +610,7 @@ static inline int alloc_cpumasks(struct cpuset *cs, struct tmpmasks *tmp) if (cs) { pmask1 = &cs->cpus_allowed; pmask2 = &cs->effective_cpus; - pmask3 = &cs->subparts_cpus; + pmask3 = &cs->exclusive_cpus; } else { pmask1 = &tmp->new_cpus; pmask2 = &tmp->addmask; @@ -636,7 +645,7 @@ static inline void free_cpumasks(struct cpuset *cs, struct tmpmasks *tmp) if (cs) { free_cpumask_var(cs->cpus_allowed); free_cpumask_var(cs->effective_cpus); - free_cpumask_var(cs->subparts_cpus); + free_cpumask_var(cs->exclusive_cpus); } if (tmp) { free_cpumask_var(tmp->new_cpus); @@ -664,6 +673,7 @@ static struct cpuset *alloc_trial_cpuset(struct cpuset *cs)
cpumask_copy(trial->cpus_allowed, cs->cpus_allowed); cpumask_copy(trial->effective_cpus, cs->effective_cpus); + cpumask_copy(trial->exclusive_cpus, cs->exclusive_cpus); return trial; }
@@ -677,6 +687,25 @@ static inline void free_cpuset(struct cpuset *cs) kfree(cs); }
+/* + * cpu_exclusive_check() - check if two cpusets are exclusive + * + * Return 0 if exclusive, -EINVAL if not + */ +static inline bool cpu_exclusive_check(struct cpuset *cs1, struct cpuset *cs2) +{ + struct cpumask *cpus1, *cpus2; + + cpus1 = cpumask_empty(cs1->exclusive_cpus) + ? cs1->cpus_allowed : cs1->exclusive_cpus; + cpus2 = cpumask_empty(cs2->exclusive_cpus) + ? cs2->cpus_allowed : cs2->exclusive_cpus; + + if (cpumask_intersects(cpus1, cpus2)) + return -EINVAL; + return 0; +} + /* * validate_change_legacy() - Validate conditions specific to legacy (v1) * behavior. @@ -776,9 +805,10 @@ static int validate_change(struct cpuset *cur, struct cpuset *trial) ret = -EINVAL; cpuset_for_each_child(c, css, par) { if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) && - c != cur && - cpumask_intersects(trial->cpus_allowed, c->cpus_allowed)) - goto out; + c != cur) { + if (cpu_exclusive_check(trial, c)) + goto out; + } if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) && c != cur && nodes_intersects(trial->mems_allowed, c->mems_allowed)) @@ -908,7 +938,7 @@ static int generate_sched_domains(cpumask_var_t **domains, csa = NULL;
/* Special case for the 99% of systems with one, full, sched domain */ - if (root_load_balance && !top_cpuset.nr_subparts_cpus) { + if (root_load_balance && !top_cpuset.nr_subparts) { ndoms = 1; doms = alloc_sched_domains(ndoms); if (!doms) @@ -1159,7 +1189,7 @@ static void rebuild_sched_domains_locked(void) * should be the same as the active CPUs, so checking only top_cpuset * is enough to detect racing CPU offlines. */ - if (!top_cpuset.nr_subparts_cpus && + if (cpumask_empty(subpartitions_cpus) && !cpumask_equal(top_cpuset.effective_cpus, cpu_active_mask)) return;
@@ -1168,7 +1198,7 @@ static void rebuild_sched_domains_locked(void) * root should be only a subset of the active CPUs. Since a CPU in any * partition root could be offlined, all must be checked. */ - if (top_cpuset.nr_subparts_cpus) { + if (top_cpuset.nr_subparts) { rcu_read_lock(); cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) { if (!is_partition_valid(cs)) { @@ -1232,7 +1262,7 @@ static void update_tasks_cpumask(struct cpuset *cs, struct cpumask *new_cpus) */ if ((task->flags & PF_KTHREAD) && kthread_is_per_cpu(task)) continue; - cpumask_andnot(new_cpus, possible_mask, cs->subparts_cpus); + cpumask_andnot(new_cpus, possible_mask, cs->exclusive_cpus); } else { cpumask_and(new_cpus, possible_mask, cs->effective_cpus); } @@ -1247,32 +1277,22 @@ static void update_tasks_cpumask(struct cpuset *cs, struct cpumask *new_cpus) * @cs: the cpuset the need to recompute the new effective_cpus mask * @parent: the parent cpuset * - * If the parent has subpartition CPUs, include them in the list of - * allowable CPUs in computing the new effective_cpus mask. Since offlined - * CPUs are not removed from subparts_cpus, we have to use cpu_active_mask - * to mask those out. + * The result is valid only if the given cpuset isn't a partition root. */ static void compute_effective_cpumask(struct cpumask *new_cpus, struct cpuset *cs, struct cpuset *parent) { - if (parent->nr_subparts_cpus && is_partition_valid(cs)) { - cpumask_or(new_cpus, parent->effective_cpus, - parent->subparts_cpus); - cpumask_and(new_cpus, new_cpus, cs->cpus_allowed); - cpumask_and(new_cpus, new_cpus, cpu_active_mask); - } else { - cpumask_and(new_cpus, cs->cpus_allowed, parent->effective_cpus); - } + cpumask_and(new_cpus, cs->cpus_allowed, parent->effective_cpus); }
/* - * Commands for update_parent_subparts_cpumask + * Commands for update_parent_effective_cpumask */ -enum subparts_cmd { - partcmd_enable, /* Enable partition root */ - partcmd_disable, /* Disable partition root */ - partcmd_update, /* Update parent's subparts_cpus */ - partcmd_invalidate, /* Make partition invalid */ +enum partition_cmd { + partcmd_enable, /* Enable partition root */ + partcmd_disable, /* Disable partition root */ + partcmd_update, /* Update parent's effective_cpus */ + partcmd_invalidate, /* Make partition invalid */ };
static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, @@ -1323,8 +1343,39 @@ static void update_partition_sd_lb(struct cpuset *cs, int old_prs) rebuild_sched_domains_locked(); }
+/* + * tasks_nocpu_error - Return true if tasks will have no effective_cpus + */ +static bool tasks_nocpu_error(struct cpuset *parent, struct cpuset *cs, + struct cpumask *xcpus) +{ + /* + * A populated partition (cs or parent) can't have empty effective_cpus + */ + return (cpumask_subset(parent->effective_cpus, xcpus) && + partition_is_populated(parent, cs)) || + (!cpumask_intersects(xcpus, cpu_active_mask) && + partition_is_populated(cs, NULL)); +} + +/* + * setup_exclusive_cpus - setup exclusive_cpus if not set yet + */ +static void setup_exclusive_cpus(struct cpuset *cs, struct cpuset *parent) +{ + if (!cpumask_empty(cs->exclusive_cpus)) + return; + + if (!parent) + parent = parent_cs(cs); + spin_lock_irq(&callback_lock); + cpumask_and(cs->exclusive_cpus, + cs->cpus_allowed, parent->exclusive_cpus); + spin_unlock_irq(&callback_lock); +} + /** - * update_parent_subparts_cpumask - update subparts_cpus mask of parent cpuset + * update_parent_effective_cpumask - update effective_cpus mask of parent cpuset * @cs: The cpuset that requests change in partition root state * @cmd: Partition root state change command * @newmask: Optional new cpumask for partcmd_update @@ -1332,21 +1383,20 @@ static void update_partition_sd_lb(struct cpuset *cs, int old_prs) * Return: 0 or a partition root state error code * * For partcmd_enable, the cpuset is being transformed from a non-partition - * root to a partition root. The cpus_allowed mask of the given cpuset will - * be put into parent's subparts_cpus and taken away from parent's + * root to a partition root. The exclusive_cpus (cpus_allowed if exclusive_cpus + * not set) mask of the given cpuset will be taken away from parent's * effective_cpus. The function will return 0 if all the CPUs listed in - * cpus_allowed can be granted or an error code will be returned. + * exclusive_cpus can be granted or an error code will be returned. * * For partcmd_disable, the cpuset is being transformed from a partition - * root back to a non-partition root. Any CPUs in cpus_allowed that are in - * parent's subparts_cpus will be taken away from that cpumask and put back - * into parent's effective_cpus. 0 will always be returned. + * root back to a non-partition root. Any CPUs in exclusive_cpus will be + * given back to parent's effective_cpus. 0 will always be returned. * * For partcmd_update, if the optional newmask is specified, the cpu list is - * to be changed from cpus_allowed to newmask. Otherwise, cpus_allowed is + * to be changed from exclusive_cpus to newmask. Otherwise, exclusive_cpus is * assumed to remain the same. The cpuset should either be a valid or invalid * partition root. The partition root state may change from valid to invalid - * or vice versa. An error code will only be returned if transitioning from + * or vice versa. An error code will be returned if transitioning from * invalid to valid violates the exclusivity rule. * * For partcmd_invalidate, the current partition will be made invalid. @@ -1361,18 +1411,47 @@ static void update_partition_sd_lb(struct cpuset *cs, int old_prs) * check for error and so partition_root_state and prs_error will be updated * directly. */ -static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, - struct cpumask *newmask, - struct tmpmasks *tmp) +static int update_parent_effective_cpumask(struct cpuset *cs, int cmd, + struct cpumask *newmask, + struct tmpmasks *tmp) { struct cpuset *parent = parent_cs(cs); - int adding; /* Moving cpus from effective_cpus to subparts_cpus */ - int deleting; /* Moving cpus from subparts_cpus to effective_cpus */ + int adding; /* Adding cpus to parent's effective_cpus */ + int deleting; /* Deleting cpus from parent's effective_cpus */ int old_prs, new_prs; int part_error = PERR_NONE; /* Partition error? */ + int subparts_delta = 0; + struct cpumask *xcpus; /* cs exclusive_cpus */ + bool nocpu;
lockdep_assert_held(&cpuset_mutex);
+ /* + * new_prs will only be changed for the partcmd_update and + * partcmd_invalidate commands. + */ + adding = deleting = false; + old_prs = new_prs = cs->partition_root_state; + xcpus = !cpumask_empty(cs->exclusive_cpus) + ? cs->exclusive_cpus : cs->cpus_allowed; + + if (cmd == partcmd_invalidate) { + if (is_prs_invalid(old_prs)) + return 0; + + /* + * Make the current partition invalid. + */ + if (is_partition_valid(parent)) + adding = cpumask_and(tmp->addmask, + xcpus, parent->exclusive_cpus); + if (old_prs > 0) { + new_prs = -old_prs; + subparts_delta--; + } + goto write_error; + } + /* * The parent must be a partition root. * The new cpumask, if present, or the current cpus_allowed must @@ -1385,124 +1464,122 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, if (!newmask && cpumask_empty(cs->cpus_allowed)) return PERR_CPUSEMPTY;
- /* - * new_prs will only be changed for the partcmd_update and - * partcmd_invalidate commands. - */ - adding = deleting = false; - old_prs = new_prs = cs->partition_root_state; + nocpu = tasks_nocpu_error(parent, cs, xcpus); + if (cmd == partcmd_enable) { /* * Enabling partition root is not allowed if cpus_allowed * doesn't overlap parent's cpus_allowed. */ - if (!cpumask_intersects(cs->cpus_allowed, parent->cpus_allowed)) + if (!cpumask_intersects(xcpus, parent->exclusive_cpus)) return PERR_INVCPUS;
/* * A parent can be left with no CPU as long as there is no * task directly associated with the parent partition. */ - if (cpumask_subset(parent->effective_cpus, cs->cpus_allowed) && - partition_is_populated(parent, cs)) + if (nocpu) return PERR_NOCPUS;
- cpumask_copy(tmp->addmask, cs->cpus_allowed); - adding = true; + cpumask_copy(tmp->delmask, xcpus); + deleting = true; + subparts_delta++; } else if (cmd == partcmd_disable) { /* - * Need to remove cpus from parent's subparts_cpus for valid - * partition root. + n* May need to add cpus to parent's effective_cpus for + * valid partition root. */ - deleting = !is_prs_invalid(old_prs) && - cpumask_and(tmp->delmask, cs->cpus_allowed, - parent->subparts_cpus); - } else if (cmd == partcmd_invalidate) { - if (is_prs_invalid(old_prs)) - return 0; - + adding = !is_prs_invalid(old_prs) && + cpumask_and(tmp->addmask, xcpus, parent->exclusive_cpus); + if (adding) + subparts_delta--; + } else if (newmask) { /* - * Make the current partition invalid. It is assumed that - * invalidation is caused by violating cpu exclusivity rule. + * Empty cpumask is not allowed */ - deleting = cpumask_and(tmp->delmask, cs->cpus_allowed, - parent->subparts_cpus); - if (old_prs > 0) { - new_prs = -old_prs; - part_error = PERR_NOTEXCL; + if (cpumask_empty(newmask)) { + part_error = PERR_CPUSEMPTY; + goto write_error; } - } else if (newmask) { + /* * partcmd_update with newmask: * - * Compute add/delete mask to/from subparts_cpus + * Compute add/delete mask to/from effective_cpus * - * delmask = cpus_allowed & ~newmask & parent->subparts_cpus - * addmask = newmask & parent->cpus_allowed - * & ~parent->subparts_cpus + * addmask = exclusive_cpus & ~newmask & parent->exclusive_cpus + * delmask = newmask & ~cs->exclusive_cpus + * & parent->exclusive_cpus */ - cpumask_andnot(tmp->delmask, cs->cpus_allowed, newmask); - deleting = cpumask_and(tmp->delmask, tmp->delmask, - parent->subparts_cpus); + cpumask_andnot(tmp->addmask, xcpus, newmask); + adding = cpumask_and(tmp->addmask, tmp->addmask, + parent->exclusive_cpus);
- cpumask_and(tmp->addmask, newmask, parent->cpus_allowed); - adding = cpumask_andnot(tmp->addmask, tmp->addmask, - parent->subparts_cpus); - /* - * Empty cpumask is not allowed - */ - if (cpumask_empty(newmask)) { - part_error = PERR_CPUSEMPTY; + cpumask_andnot(tmp->delmask, newmask, xcpus); + deleting = cpumask_and(tmp->delmask, tmp->delmask, + parent->exclusive_cpus); /* * Make partition invalid if parent's effective_cpus could * become empty and there are tasks in the parent. */ - } else if (adding && - cpumask_subset(parent->effective_cpus, tmp->addmask) && - !cpumask_intersects(tmp->delmask, cpu_active_mask) && - partition_is_populated(parent, cs)) { + if (nocpu && (!adding || + !cpumask_intersects(tmp->addmask, cpu_active_mask))) { part_error = PERR_NOCPUS; - adding = false; - deleting = cpumask_and(tmp->delmask, cs->cpus_allowed, - parent->subparts_cpus); + deleting = false; + adding = cpumask_and(tmp->addmask, + xcpus, parent->exclusive_cpus); } } else { /* - * partcmd_update w/o newmask: + * partcmd_update w/o newmask + * + * delmask = exclusive_cpus & parent->effective_cpus + * + * This can be called from: + * 1) update_cpumasks_hier() + * 2) cpuset_hotplug_update_tasks() * - * delmask = cpus_allowed & parent->subparts_cpus - * addmask = cpus_allowed & parent->cpus_allowed - * & ~parent->subparts_cpus + * Check to see if it can be transitioned from valid to + * invalid partition or vice versa. * - * This gets invoked either due to a hotplug event or from - * update_cpumasks_hier(). This can cause the state of a - * partition root to transition from valid to invalid or vice - * versa. So we still need to compute the addmask and delmask. - - * A partition error happens when: - * 1) Cpuset is valid partition, but parent does not distribute - * out any CPUs. - * 2) Parent has tasks and all its effective CPUs will have - * to be distributed out. + * A partition error happens when parent has tasks and all + * its effective CPUs will have to be distributed out. */ - cpumask_and(tmp->addmask, cs->cpus_allowed, - parent->cpus_allowed); - adding = cpumask_andnot(tmp->addmask, tmp->addmask, - parent->subparts_cpus); - - if ((is_partition_valid(cs) && !parent->nr_subparts_cpus) || - (adding && - cpumask_subset(parent->effective_cpus, tmp->addmask) && - partition_is_populated(parent, cs))) { + WARN_ON_ONCE(!is_partition_valid(parent)); + if (nocpu) { part_error = PERR_NOCPUS; - adding = false; - } + if (is_partition_valid(cs)) + adding = cpumask_and(tmp->addmask, + xcpus, parent->exclusive_cpus); + } else if (is_partition_invalid(cs) && + cpumask_subset(xcpus, parent->exclusive_cpus)) { + struct cgroup_subsys_state *css; + struct cpuset *child; + bool exclusive = true;
- if (part_error && is_partition_valid(cs) && - parent->nr_subparts_cpus) - deleting = cpumask_and(tmp->delmask, cs->cpus_allowed, - parent->subparts_cpus); + /* + * Convert invalid partition to valid has to + * pass the cpu exclusivity test. + */ + rcu_read_lock(); + cpuset_for_each_child(child, css, parent) { + if (child == cs) + continue; + if (cpu_exclusive_check(cs, child)) { + exclusive = false; + break; + } + } + rcu_read_unlock(); + if (exclusive) + deleting = cpumask_and(tmp->delmask, + xcpus, parent->effective_cpus); + else + part_error = PERR_NOTEXCL; + } } + +write_error: if (part_error) WRITE_ONCE(cs->prs_err, part_error);
@@ -1514,13 +1591,17 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, switch (cs->partition_root_state) { case PRS_ROOT: case PRS_ISOLATED: - if (part_error) + if (part_error) { new_prs = -old_prs; + subparts_delta--; + } break; case PRS_INVALID_ROOT: case PRS_INVALID_ISOLATED: - if (!part_error) + if (!part_error) { new_prs = -old_prs; + subparts_delta++; + } break; } } @@ -1540,32 +1621,43 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, }
/* - * Change the parent's subparts_cpus. + * Change the parent's effective_cpus & exclusive_cpus (top cpuset + * only). + * * Newly added CPUs will be removed from effective_cpus and * newly deleted ones will be added back to effective_cpus. */ spin_lock_irq(&callback_lock); if (adding) { - cpumask_or(parent->subparts_cpus, - parent->subparts_cpus, tmp->addmask); - cpumask_andnot(parent->effective_cpus, - parent->effective_cpus, tmp->addmask); - } - if (deleting) { - cpumask_andnot(parent->subparts_cpus, - parent->subparts_cpus, tmp->delmask); + if (parent == &top_cpuset) + cpumask_andnot(subpartitions_cpus, + subpartitions_cpus, tmp->addmask); /* - * Some of the CPUs in subparts_cpus might have been offlined. + * Some of the CPUs in exclusive_cpus might have been offlined. */ - cpumask_and(tmp->delmask, tmp->delmask, cpu_active_mask); cpumask_or(parent->effective_cpus, - parent->effective_cpus, tmp->delmask); + parent->effective_cpus, tmp->addmask); + cpumask_and(parent->effective_cpus, + parent->effective_cpus, cpu_active_mask); + } + if (deleting) { + if (parent == &top_cpuset) + cpumask_or(subpartitions_cpus, + subpartitions_cpus, tmp->delmask); + cpumask_andnot(parent->effective_cpus, + parent->effective_cpus, tmp->delmask); }
- parent->nr_subparts_cpus = cpumask_weight(parent->subparts_cpus); + if (is_partition_valid(parent)) { + parent->nr_subparts += subparts_delta; + WARN_ON_ONCE(parent->nr_subparts < 0); + }
- if (old_prs != new_prs) + if (old_prs != new_prs) { cs->partition_root_state = new_prs; + if (new_prs <= 0) + cs->nr_subparts = 0; + }
spin_unlock_irq(&callback_lock);
@@ -1590,6 +1682,71 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd, return 0; }
+/** + * compute_partition_effective_cpumask - compute effective_cpus for partition + * @cs: partition root cpuset + * @new_ecpus: previously computed effective_cpus to be updated + * + * Compute the effective_cpus of a partition root by scanning exclusive_cpus + * of child partition roots and exclusing their exclusive_cpus. + * + * This has the side effect of invalidating valid child partition roots, + * if necessary. Since it is called from either cpuset_hotplug_update_tasks() + * or update_cpumasks_hier() where parent and children are modified + * successively, we don't need to call update_parent_effective_cpumask() + * and the child's effective_cpus will be updated in later iterations. + * + * Note that rcu_read_lock() is assumed to be held. + */ +static void compute_partition_effective_cpumask(struct cpuset *cs, + struct cpumask *new_ecpus) +{ + struct cgroup_subsys_state *css; + struct cpuset *child; + bool populated = partition_is_populated(cs, NULL); + + /* + * Check child partition roots to see if they should be + * invalidated when + * 1) child exclusive_cpus not a subset of new + * excluisve_cpus + * 2) All the effective_cpus will be used up and cp + * has tasks + */ + cpumask_and(new_ecpus, cs->exclusive_cpus, cpu_active_mask); + rcu_read_lock(); + cpuset_for_each_child(child, css, cs) { + if (!is_partition_valid(child)) + continue; + + child->prs_err = 0; + if (!cpumask_subset(child->exclusive_cpus, + cs->exclusive_cpus)) + child->prs_err = PERR_INVCPUS; + else if (populated && + cpumask_subset(new_ecpus, child->exclusive_cpus)) + child->prs_err = PERR_NOCPUS; + + if (child->prs_err) { + int old_prs = child->partition_root_state; + + /* + * Invalidate child partition + */ + spin_lock_irq(&callback_lock); + make_partition_invalid(child); + cs->nr_subparts--; + child->nr_subparts = 0; + spin_unlock_irq(&callback_lock); + notify_partition_change(child, old_prs); + continue; + } + cpumask_andnot(new_ecpus, new_ecpus, + child->exclusive_cpus); + } + rcu_read_unlock(); +} + /* * update_cpumasks_hier() flags */ @@ -1624,6 +1781,19 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp,
compute_effective_cpumask(tmp->new_cpus, cp, parent);
+ if (is_partition_valid(parent) && is_partition_valid(cp)) + compute_partition_effective_cpumask(cp, tmp->new_cpus); + + /* + * A partition with no effective_cpus is allowed as long as + * there is no task associated with it. Call + * update_parent_effective_cpumask() to check it. + */ + if (is_partition_valid(cp) && cpumask_empty(tmp->new_cpus)) { + update_parent = true; + goto update_parent_effective; + } + /* * If it becomes empty, inherit the effective mask of the * parent, which is guaranteed to have some CPUs unless @@ -1631,10 +1801,6 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp, * out all its CPUs. */ if (is_in_v2_mode() && cpumask_empty(tmp->new_cpus)) { - if (is_partition_valid(cp) && - cpumask_equal(cp->cpus_allowed, cp->subparts_cpus)) - goto update_parent_subparts; - cpumask_copy(tmp->new_cpus, parent->effective_cpus); if (!cp->use_parent_ecpus) { cp->use_parent_ecpus = true; @@ -1661,12 +1827,12 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp, continue; }
-update_parent_subparts: +update_parent_effective: /* - * update_parent_subparts_cpumask() should have been called + * update_parent_effective_cpumask() should have been called * for cs already in update_cpumask(). We should also call * update_tasks_cpumask() again for tasks in the parent - * cpuset if the parent's subparts_cpus changes. + * cpuset if the parent's effective_cpus changes. */ old_prs = new_prs = cp->partition_root_state; if ((cp != cs) && old_prs) { @@ -1696,8 +1862,7 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp, rcu_read_unlock();
if (update_parent) { - update_parent_subparts_cpumask(cp, partcmd_update, NULL, - tmp); + update_parent_effective_cpumask(cp, partcmd_update, NULL, tmp); /* * The cpuset partition_root_state may become * invalid. Capture it. @@ -1706,30 +1871,18 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp, }
spin_lock_irq(&callback_lock); - - if (cp->nr_subparts_cpus && !is_partition_valid(cp)) { - /* - * Put all active subparts_cpus back to effective_cpus. - */ - cpumask_or(tmp->new_cpus, tmp->new_cpus, - cp->subparts_cpus); - cpumask_and(tmp->new_cpus, tmp->new_cpus, - cpu_active_mask); - cp->nr_subparts_cpus = 0; - cpumask_clear(cp->subparts_cpus); - } - cpumask_copy(cp->effective_cpus, tmp->new_cpus); - if (cp->nr_subparts_cpus) { - /* - * Make sure that effective_cpus & subparts_cpus - * are mutually exclusive. - */ - cpumask_andnot(cp->effective_cpus, cp->effective_cpus, - cp->subparts_cpus); - } - cp->partition_root_state = new_prs; + if ((new_prs > 0) && cpumask_empty(cp->exclusive_cpus)) + cpumask_and(cp->exclusive_cpus, + cp->cpus_allowed, parent->exclusive_cpus); + if (new_prs < 0) { + /* Reset partition data */ + cp->nr_subparts = 0; + cpumask_clear(cp->exclusive_cpus); + if (is_cpu_exclusive(cp)) + clear_bit(CS_CPU_EXCLUSIVE, &cp->flags); + } spin_unlock_irq(&callback_lock);
notify_partition_change(cp, old_prs); @@ -1826,6 +1979,7 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs, { int retval; struct tmpmasks tmp; + struct cpuset *parent = parent_cs(cs); bool invalidate = false; int old_prs = cs->partition_root_state;
@@ -1841,6 +1995,7 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs, */ if (!*buf) { cpumask_clear(trialcs->cpus_allowed); + cpumask_clear(trialcs->exclusive_cpus); } else { retval = cpulist_parse(buf, trialcs->cpus_allowed); if (retval < 0) @@ -1849,6 +2004,13 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs, if (!cpumask_subset(trialcs->cpus_allowed, top_cpuset.cpus_allowed)) return -EINVAL; + + /* + * When exclusive_cpus is set, make sure it is a subset of + * cpus_allowed and parent's exclusive_cpus. + */ + cpumask_and(trialcs->exclusive_cpus, + parent->exclusive_cpus, trialcs->cpus_allowed); }
/* Nothing to do if the cpus didn't change */ @@ -1858,11 +2020,21 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs, if (alloc_cpumasks(NULL, &tmp)) return -ENOMEM;
+ if (is_partition_valid(cs)) { + if (cpumask_empty(trialcs->exclusive_cpus)) { + invalidate = true; + cs->prs_err = PERR_INVCPUS; + } else if (tasks_nocpu_error(parent, cs, trialcs->exclusive_cpus)) { + invalidate = true; + cs->prs_err = PERR_NOCPUS; + } + } + retval = validate_change(cs, trialcs);
if ((retval == -EINVAL) && cgroup_subsys_on_dfl(cpuset_cgrp_subsys)) { - struct cpuset *cp, *parent; struct cgroup_subsys_state *css; + struct cpuset *cp;
/* * The -EINVAL error code indicates that partition sibling @@ -1873,69 +2045,44 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs, */ invalidate = true; rcu_read_lock(); - parent = parent_cs(cs); cpuset_for_each_child(cp, css, parent) if (is_partition_valid(cp) && - cpumask_intersects(trialcs->cpus_allowed, cp->cpus_allowed)) { + cpumask_intersects(trialcs->exclusive_cpus, cp->exclusive_cpus)) { rcu_read_unlock(); - update_parent_subparts_cpumask(cp, partcmd_invalidate, NULL, &tmp); + update_parent_effective_cpumask(cp, partcmd_invalidate, NULL, &tmp); rcu_read_lock(); } rcu_read_unlock(); retval = 0; } + if (retval < 0) goto out_free;
if (cs->partition_root_state) { if (invalidate) - update_parent_subparts_cpumask(cs, partcmd_invalidate, - NULL, &tmp); + update_parent_effective_cpumask(cs, partcmd_invalidate, + NULL, &tmp); else - update_parent_subparts_cpumask(cs, partcmd_update, - trialcs->cpus_allowed, &tmp); + update_parent_effective_cpumask(cs, partcmd_update, + trialcs->exclusive_cpus, &tmp); }
- compute_effective_cpumask(trialcs->effective_cpus, trialcs, - parent_cs(cs)); spin_lock_irq(&callback_lock); cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed); + if (!is_partition_valid(cs)) + cpumask_clear(cs->exclusive_cpus); + else + cpumask_copy(cs->exclusive_cpus, trialcs->exclusive_cpus);
- /* - * Make sure that subparts_cpus, if not empty, is a subset of - * cpus_allowed. Clear subparts_cpus if partition not valid or - * empty effective cpus with tasks. - */ - if (cs->nr_subparts_cpus) { - if (!is_partition_valid(cs) || - (cpumask_subset(trialcs->effective_cpus, cs->subparts_cpus) && - partition_is_populated(cs, NULL))) { - cs->nr_subparts_cpus = 0; - cpumask_clear(cs->subparts_cpus); - } else { - cpumask_and(cs->subparts_cpus, cs->subparts_cpus, - cs->cpus_allowed); - cs->nr_subparts_cpus = cpumask_weight(cs->subparts_cpus); - } - } spin_unlock_irq(&callback_lock);
/* effective_cpus will be updated here */ update_cpumasks_hier(cs, &tmp, 0);
- if (cs->partition_root_state) { - struct cpuset *parent = parent_cs(cs); - - /* - * For partition root, update the cpumasks of sibling - * cpusets if they use parent's effective_cpus. - */ - if (parent->child_ecpus_count) - update_sibling_cpumasks(parent, cs, &tmp); - - /* Update CS_SCHED_LOAD_BALANCE and/or sched_domains */ + /* Update CS_SCHED_LOAD_BALANCE and/or sched_domains, if necessary */ + if (cs->partition_root_state) update_partition_sd_lb(cs, old_prs); - } out_free: free_cpumasks(NULL, &tmp); return 0; @@ -2313,7 +2460,6 @@ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, static int update_prstate(struct cpuset *cs, int new_prs) { int err = PERR_NONE, old_prs = cs->partition_root_state; - struct cpuset *parent = parent_cs(cs); struct tmpmasks tmpmask;
if (old_prs == new_prs) @@ -2331,6 +2477,13 @@ static int update_prstate(struct cpuset *cs, int new_prs) if (alloc_cpumasks(NULL, &tmpmask)) return -ENOMEM;
+ /* + * Setup exclusive_cpus if not set yet, it will be cleared later + * if partition becomes invalid. + */ + if (new_prs > 0) + setup_exclusive_cpus(cs, NULL); + err = update_partition_exclusive(cs, new_prs); if (err) goto out; @@ -2344,8 +2497,8 @@ static int update_prstate(struct cpuset *cs, int new_prs) goto out; }
- err = update_parent_subparts_cpumask(cs, partcmd_enable, - NULL, &tmpmask); + err = update_parent_effective_cpumask(cs, partcmd_enable, + NULL, &tmpmask); } else if (old_prs && new_prs) { /* * A change in load balance state only, no change in cpumasks. @@ -2356,19 +2509,13 @@ static int update_prstate(struct cpuset *cs, int new_prs) * Switching back to member is always allowed even if it * disables child partitions. */ - update_parent_subparts_cpumask(cs, partcmd_disable, NULL, - &tmpmask); + update_parent_effective_cpumask(cs, partcmd_disable, NULL, + &tmpmask);
/* - * If there are child partitions, they will all become invalid. + * Invalidation of child partitions will be done in + * update_cpumasks_hier(). */ - if (unlikely(cs->nr_subparts_cpus)) { - spin_lock_irq(&callback_lock); - cs->nr_subparts_cpus = 0; - cpumask_clear(cs->subparts_cpus); - compute_effective_cpumask(cs->effective_cpus, cs, parent); - spin_unlock_irq(&callback_lock); - } } out: /* @@ -2383,14 +2530,12 @@ static int update_prstate(struct cpuset *cs, int new_prs) spin_lock_irq(&callback_lock); cs->partition_root_state = new_prs; WRITE_ONCE(cs->prs_err, err); + if (!is_partition_valid(cs)) + cpumask_clear(cs->exclusive_cpus); spin_unlock_irq(&callback_lock);
- /* - * Update child cpusets, if present. - * Force update if switching back to member. - */ - if (!list_empty(&cs->css.children)) - update_cpumasks_hier(cs, &tmpmask, !new_prs ? HIER_CHECKALL : 0); + /* Force update if switching back to member */ + update_cpumasks_hier(cs, &tmpmask, !new_prs ? HIER_CHECKALL : 0);
/* Update sched domains and load balance flag */ update_partition_sd_lb(cs, old_prs); @@ -2626,7 +2771,7 @@ static void cpuset_attach_task(struct cpuset *cs, struct task_struct *task) guarantee_online_cpus(task, cpus_attach); else cpumask_andnot(cpus_attach, task_cpu_possible_mask(task), - cs->subparts_cpus); + subpartitions_cpus); /* * can_attach beforehand should guarantee that this doesn't * fail. TODO: have a better way to handle failure here @@ -2729,6 +2874,7 @@ typedef enum { FILE_EFFECTIVE_CPULIST, FILE_EFFECTIVE_MEMLIST, FILE_SUBPARTS_CPULIST, + FILE_EXCLUSIVE_CPULIST, FILE_CPU_EXCLUSIVE, FILE_MEM_EXCLUSIVE, FILE_MEM_HARDWALL, @@ -2913,8 +3059,11 @@ static int cpuset_common_seq_show(struct seq_file *sf, void *v) case FILE_EFFECTIVE_MEMLIST: seq_printf(sf, "%*pbl\n", nodemask_pr_args(&cs->effective_mems)); break; + case FILE_EXCLUSIVE_CPULIST: + seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->exclusive_cpus)); + break; case FILE_SUBPARTS_CPULIST: - seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->subparts_cpus)); + seq_printf(sf, "%*pbl\n", cpumask_pr_args(subpartitions_cpus)); break; default: ret = -EINVAL; @@ -3186,11 +3335,18 @@ static struct cftype dfl_files[] = { .file_offset = offsetof(struct cpuset, partition_file), },
+ { + .name = "cpus.exclusive", + .seq_show = cpuset_common_seq_show, + .private = FILE_EXCLUSIVE_CPULIST, + .flags = CFTYPE_NOT_ON_ROOT, + }, + { .name = "cpus.subpartitions", .seq_show = cpuset_common_seq_show, .private = FILE_SUBPARTS_CPULIST, - .flags = CFTYPE_DEBUG, + .flags = CFTYPE_ONLY_ON_ROOT | CFTYPE_DEBUG, },
{ } /* terminate */ @@ -3364,6 +3520,7 @@ static void cpuset_bind(struct cgroup_subsys_state *root_css)
if (is_in_v2_mode()) { cpumask_copy(top_cpuset.cpus_allowed, cpu_possible_mask); + cpumask_copy(top_cpuset.exclusive_cpus, cpu_possible_mask); top_cpuset.mems_allowed = node_possible_map; } else { cpumask_copy(top_cpuset.cpus_allowed, @@ -3502,11 +3659,13 @@ int __init cpuset_init(void) { BUG_ON(!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL)); BUG_ON(!alloc_cpumask_var(&top_cpuset.effective_cpus, GFP_KERNEL)); - BUG_ON(!zalloc_cpumask_var(&top_cpuset.subparts_cpus, GFP_KERNEL)); + BUG_ON(!alloc_cpumask_var(&top_cpuset.exclusive_cpus, GFP_KERNEL)); + BUG_ON(!zalloc_cpumask_var(&subpartitions_cpus, GFP_KERNEL));
cpumask_setall(top_cpuset.cpus_allowed); nodes_setall(top_cpuset.mems_allowed); cpumask_setall(top_cpuset.effective_cpus); + cpumask_setall(top_cpuset.exclusive_cpus); nodes_setall(top_cpuset.effective_mems);
fmeter_init(&top_cpuset.fmeter); @@ -3647,30 +3806,15 @@ static void cpuset_hotplug_update_tasks(struct cpuset *cs, struct tmpmasks *tmp) compute_effective_cpumask(&new_cpus, cs, parent); nodes_and(new_mems, cs->mems_allowed, parent->effective_mems);
- if (cs->nr_subparts_cpus) - /* - * Make sure that CPUs allocated to child partitions - * do not show up in effective_cpus. - */ - cpumask_andnot(&new_cpus, &new_cpus, cs->subparts_cpus); - if (!tmp || !cs->partition_root_state) goto update_tasks;
/* - * In the unlikely event that a partition root has empty - * effective_cpus with tasks, we will have to invalidate child - * partitions, if present, by setting nr_subparts_cpus to 0 to - * reclaim their cpus. + * Compute effective_cpus for valid partition root, may invalidate + * child partition roots if necessary. */ - if (cs->nr_subparts_cpus && is_partition_valid(cs) && - cpumask_empty(&new_cpus) && partition_is_populated(cs, NULL)) { - spin_lock_irq(&callback_lock); - cs->nr_subparts_cpus = 0; - cpumask_clear(cs->subparts_cpus); - spin_unlock_irq(&callback_lock); - compute_effective_cpumask(&new_cpus, cs, parent); - } + if (is_partition_valid(cs) && is_partition_valid(parent)) + compute_partition_effective_cpumask(cs, &new_cpus);
/* * Force the partition to become invalid if either one of @@ -3679,44 +3823,23 @@ static void cpuset_hotplug_update_tasks(struct cpuset *cs, struct tmpmasks *tmp) * 2) parent is invalid or doesn't grant any cpus to child * partitions. */ - if (is_partition_valid(cs) && (!parent->nr_subparts_cpus || - (cpumask_empty(&new_cpus) && partition_is_populated(cs, NULL)))) { - int old_prs, parent_prs; - - update_parent_subparts_cpumask(cs, partcmd_disable, NULL, tmp); - if (cs->nr_subparts_cpus) { - spin_lock_irq(&callback_lock); - cs->nr_subparts_cpus = 0; - cpumask_clear(cs->subparts_cpus); - spin_unlock_irq(&callback_lock); - compute_effective_cpumask(&new_cpus, cs, parent); - } - - old_prs = cs->partition_root_state; - parent_prs = parent->partition_root_state; - if (is_partition_valid(cs)) { - spin_lock_irq(&callback_lock); - make_partition_invalid(cs); - spin_unlock_irq(&callback_lock); - if (is_prs_invalid(parent_prs)) - WRITE_ONCE(cs->prs_err, PERR_INVPARENT); - else if (!parent_prs) - WRITE_ONCE(cs->prs_err, PERR_NOTPART); - else - WRITE_ONCE(cs->prs_err, PERR_HOTPLUG); - notify_partition_change(cs, old_prs); - } + if (is_partition_valid(cs) && (!is_partition_valid(parent) || + tasks_nocpu_error(parent, cs, &new_cpus))) { + update_parent_effective_cpumask(cs, partcmd_invalidate, NULL, tmp); + compute_effective_cpumask(&new_cpus, cs, parent); cpuset_force_rebuild(); } - /* * On the other hand, an invalid partition root may be transitioned * back to a regular one. */ else if (is_partition_valid(parent) && is_partition_invalid(cs)) { - update_parent_subparts_cpumask(cs, partcmd_update, NULL, tmp); - if (is_partition_valid(cs)) + update_parent_effective_cpumask(cs, partcmd_update, NULL, tmp); + if (is_partition_valid(cs)) { + setup_exclusive_cpus(cs, parent); + compute_partition_effective_cpumask(cs, &new_cpus); cpuset_force_rebuild(); + } }
update_tasks: @@ -3773,21 +3896,22 @@ static void cpuset_hotplug_workfn(struct work_struct *work) new_mems = node_states[N_MEMORY];
/* - * If subparts_cpus is populated, it is likely that the check below - * will produce a false positive on cpus_updated when the cpu list - * isn't changed. It is extra work, but it is better to be safe. + * If subpartitions_cpus is populated, it is likely that the check + * below will produce a false positive on cpus_updated when the cpu + * list isn't changed. It is extra work, but it is better to be safe. */ - cpus_updated = !cpumask_equal(top_cpuset.effective_cpus, &new_cpus); + cpus_updated = !cpumask_equal(top_cpuset.effective_cpus, &new_cpus) || + !cpumask_empty(subpartitions_cpus); mems_updated = !nodes_equal(top_cpuset.effective_mems, new_mems);
/* - * In the rare case that hotplug removes all the cpus in subparts_cpus, - * we assumed that cpus are updated. + * In the rare case that hotplug removes all the cpus in + * subpartitions_cpus, we assumed that cpus are updated. */ - if (!cpus_updated && top_cpuset.nr_subparts_cpus) + if (!cpus_updated && top_cpuset.nr_subparts) cpus_updated = true;
- /* synchronize cpus_allowed to cpu_active_mask */ + /* For v1, synchronize cpus_allowed to cpu_active_mask */ if (cpus_updated) { spin_lock_irq(&callback_lock); if (!on_dfl) @@ -3795,17 +3919,16 @@ static void cpuset_hotplug_workfn(struct work_struct *work) /* * Make sure that CPUs allocated to child partitions * do not show up in effective_cpus. If no CPU is left, - * we clear the subparts_cpus & let the child partitions + * we clear the subpartitions_cpus & let the child partitions * fight for the CPUs again. */ - if (top_cpuset.nr_subparts_cpus) { - if (cpumask_subset(&new_cpus, - top_cpuset.subparts_cpus)) { - top_cpuset.nr_subparts_cpus = 0; - cpumask_clear(top_cpuset.subparts_cpus); + if (!cpumask_empty(subpartitions_cpus)) { + if (cpumask_subset(&new_cpus, subpartitions_cpus)) { + top_cpuset.nr_subparts = 0; + cpumask_clear(subpartitions_cpus); } else { cpumask_andnot(&new_cpus, &new_cpus, - top_cpuset.subparts_cpus); + subpartitions_cpus); } } cpumask_copy(top_cpuset.effective_cpus, &new_cpus); @@ -3937,7 +4060,7 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask) * We first exclude cpus allocated to partitions. If there is no * allowable online cpu left, we fall back to all possible cpus. */ - cpumask_andnot(pmask, possible_mask, top_cpuset.subparts_cpus); + cpumask_andnot(pmask, possible_mask, subpartitions_cpus); if (!cpumask_intersects(pmask, cpu_online_mask)) cpumask_copy(pmask, possible_mask); }