diff options
Diffstat (limited to 'kernel/cpuset.c')
| -rw-r--r-- | kernel/cpuset.c | 107 |
1 files changed, 46 insertions, 61 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c index d94a8f7c4c2..20cb3916c66 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -38,7 +38,6 @@ #include <linux/mount.h> #include <linux/namei.h> #include <linux/pagemap.h> -#include <linux/prio_heap.h> #include <linux/proc_fs.h> #include <linux/rcupdate.h> #include <linux/sched.h> @@ -740,22 +739,50 @@ static inline int started_after(void *p1, void *p2) return started_after_time(t1, &t2->start_time, t2); } -/* +/** + * cpuset_test_cpumask - test a task's cpus_allowed versus its cpuset's + * @tsk: task to test + * @scan: struct cgroup_scanner contained in its struct cpuset_hotplug_scanner + * * Call with manage_mutex held. May take callback_mutex during call. + * Called for each task in a cgroup by cgroup_scan_tasks(). + * Return nonzero if this tasks's cpus_allowed mask should be changed (in other + * words, if its mask is not equal to its cpuset's mask). */ +int cpuset_test_cpumask(struct task_struct *tsk, struct cgroup_scanner *scan) +{ + return !cpus_equal(tsk->cpus_allowed, + (cgroup_cs(scan->cg))->cpus_allowed); +} +/** + * cpuset_change_cpumask - make a task's cpus_allowed the same as its cpuset's + * @tsk: task to test + * @scan: struct cgroup_scanner containing the cgroup of the task + * + * Called by cgroup_scan_tasks() for each task in a cgroup whose + * cpus_allowed mask needs to be changed. + * + * We don't need to re-check for the cgroup/cpuset membership, since we're + * holding cgroup_lock() at this point. + */ +void cpuset_change_cpumask(struct task_struct *tsk, struct cgroup_scanner *scan) +{ + set_cpus_allowed(tsk, (cgroup_cs(scan->cg))->cpus_allowed); +} + +/** + * update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it + * @cs: the cpuset to consider + * @buf: buffer of cpu numbers written to this cpuset + */ static int update_cpumask(struct cpuset *cs, char *buf) { struct cpuset trialcs; - int retval, i; - int is_load_balanced; - struct cgroup_iter it; - struct cgroup *cgrp = cs->css.cgroup; - struct task_struct *p, *dropped; - /* Never dereference latest_task, since it's not refcounted */ - struct task_struct *latest_task = NULL; + struct cgroup_scanner scan; struct ptr_heap heap; - struct timespec latest_time = { 0, 0 }; + int retval; + int is_load_balanced; /* top_cpuset.cpus_allowed tracks cpu_online_map; it's read-only */ if (cs == &top_cpuset) @@ -764,7 +791,7 @@ static int update_cpumask(struct cpuset *cs, char *buf) trialcs = *cs; /* - * An empty cpus_allowed is ok iff there are no tasks in the cpuset. + * An empty cpus_allowed is ok if there are no tasks in the cpuset. * Since cpulist_parse() fails on an empty mask, we special case * that parsing. The validate_change() call ensures that cpusets * with tasks have cpus. @@ -785,6 +812,7 @@ static int update_cpumask(struct cpuset *cs, char *buf) /* Nothing to do if the cpus didn't change */ if (cpus_equal(cs->cpus_allowed, trialcs.cpus_allowed)) return 0; + retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, &started_after); if (retval) return retval; @@ -795,62 +823,19 @@ static int update_cpumask(struct cpuset *cs, char *buf) cs->cpus_allowed = trialcs.cpus_allowed; mutex_unlock(&callback_mutex); - again: /* * Scan tasks in the cpuset, and update the cpumasks of any - * that need an update. Since we can't call set_cpus_allowed() - * while holding tasklist_lock, gather tasks to be processed - * in a heap structure. If the statically-sized heap fills up, - * overflow tasks that started later, and in future iterations - * only consider tasks that started after the latest task in - * the previous pass. This guarantees forward progress and - * that we don't miss any tasks + * that need an update. */ - heap.size = 0; - cgroup_iter_start(cgrp, &it); - while ((p = cgroup_iter_next(cgrp, &it))) { - /* Only affect tasks that don't have the right cpus_allowed */ - if (cpus_equal(p->cpus_allowed, cs->cpus_allowed)) - continue; - /* - * Only process tasks that started after the last task - * we processed - */ - if (!started_after_time(p, &latest_time, latest_task)) - continue; - dropped = heap_insert(&heap, p); - if (dropped == NULL) { - get_task_struct(p); - } else if (dropped != p) { - get_task_struct(p); - put_task_struct(dropped); - } - } - cgroup_iter_end(cgrp, &it); - if (heap.size) { - for (i = 0; i < heap.size; i++) { - struct task_struct *p = heap.ptrs[i]; - if (i == 0) { - latest_time = p->start_time; - latest_task = p; - } - set_cpus_allowed(p, cs->cpus_allowed); - put_task_struct(p); - } - /* - * If we had to process any tasks at all, scan again - * in case some of them were in the middle of forking - * children that didn't notice the new cpumask - * restriction. Not the most efficient way to do it, - * but it avoids having to take callback_mutex in the - * fork path - */ - goto again; - } + scan.cg = cs->css.cgroup; + scan.test_task = cpuset_test_cpumask; + scan.process_task = cpuset_change_cpumask; + scan.heap = &heap; + cgroup_scan_tasks(&scan); heap_free(&heap); + if (is_load_balanced) rebuild_sched_domains(); - return 0; } |