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Commit b4501295 authored by Paul Jackson's avatar Paul Jackson Committed by Linus Torvalds
Browse files

hotplug cpu move tasks in empty cpusets - refinements 



- Narrow the scope of callback_mutex in scan_for_empty_cpusets().

- Avoid rewriting the cpus, mems of cpusets except when it is likely that
  we'll be changing them.

- Have remove_tasks_in_empty_cpuset() also check for empty mems.

Signed-off-by: default avatarPaul Jackson <pj@sgi.com>
Acked-by: default avatarCliff Wickman <cpw@sgi.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Paul Menage <menage@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c8d9c90c

kernel/cpuset.c

+13 −8
Original line number Diff line number Diff line
@@ -1709,7 +1709,8 @@ static void remove_tasks_in_empty_cpuset(struct cpuset *cs) 
	 * has online cpus, so can't be empty).

	 */

	parent = cs->parent;

	while (cpus_empty(parent->cpus_allowed))

	while (cpus_empty(parent->cpus_allowed) ||

			nodes_empty(parent->mems_allowed))

		parent = parent->parent;



	move_member_tasks_to_cpuset(cs, parent);
@@ -1741,7 +1742,6 @@ static void scan_for_empty_cpusets(const struct cpuset *root) 


	list_add_tail((struct list_head *)&root->stack_list, &queue);



	mutex_lock(&callback_mutex);

	while (!list_empty(&queue)) {

		cp = container_of(queue.next, struct cpuset, stack_list);

		list_del(queue.next);
@@ -1750,19 +1750,24 @@ static void scan_for_empty_cpusets(const struct cpuset *root) 
			list_add_tail(&child->stack_list, &queue);

		}

		cont = cp->css.cgroup;



		/* Continue past cpusets with all cpus, mems online */

		if (cpus_subset(cp->cpus_allowed, cpu_online_map) &&

		    nodes_subset(cp->mems_allowed, node_states[N_HIGH_MEMORY]))

			continue;



		/* Remove offline cpus and mems from this cpuset. */

		mutex_lock(&callback_mutex);

		cpus_and(cp->cpus_allowed, cp->cpus_allowed, cpu_online_map);

		nodes_and(cp->mems_allowed, cp->mems_allowed,

						node_states[N_HIGH_MEMORY]);

		if (cpus_empty(cp->cpus_allowed) ||

		     nodes_empty(cp->mems_allowed)) {

			/* Move tasks from the empty cpuset to a parent */

		mutex_unlock(&callback_mutex);



		/* Move tasks from the empty cpuset to a parent */

		if (cpus_empty(cp->cpus_allowed) ||

		     nodes_empty(cp->mems_allowed))

			remove_tasks_in_empty_cpuset(cp);

			mutex_lock(&callback_mutex);

		}

	}

	mutex_unlock(&callback_mutex);

}



/*