Commit d5cf4d34 authored by Waiman Long's avatar Waiman Long Committed by Tejun Heo
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cgroup/cpuset: Don't track # of local child partitions 



The cpuset structure has a nr_subparts field which tracks the number
of child local partitions underneath a particular cpuset. Right now,
nr_subparts is only used in partition_is_populated() to avoid iteration
of child cpusets if the condition is right. So by always performing the
child iteration, we can avoid tracking the number of child partitions
and simplify the code a bit.

Signed-off-by: default avatarWaiman Long <longman@redhat.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 211ddde0

kernel/cgroup/cpuset-internal.h

+0 −3
Original line number Diff line number Diff line
@@ -155,9 +155,6 @@ struct cpuset { 
	/* for custom sched domain */

	int relax_domain_level;



	/* number of valid local child partitions */

	int nr_subparts;



	/* partition root state */

	int partition_root_state;

kernel/cgroup/cpuset.c

+13 −28
Original line number Diff line number Diff line
@@ -358,8 +358,13 @@ static inline bool is_in_v2_mode(void) 
 * @excluded_child: a child cpuset to be excluded in task checking

 * Return: true if there are tasks, false otherwise

 *

 * It is assumed that @cs is a valid partition root. @excluded_child should

 * be non-NULL when this cpuset is going to become a partition itself.

 * @cs should be a valid partition root or going to become a partition root.

 * @excluded_child should be non-NULL when this cpuset is going to become a

 * partition itself.

 *

 * Note that a remote partition is not allowed underneath a valid local

 * or remote partition. So if a non-partition root child is populated,

 * the whole partition is considered populated.

 */

static inline bool partition_is_populated(struct cpuset *cs,

					  struct cpuset *excluded_child)
@@ -369,8 +374,6 @@ static inline bool partition_is_populated(struct cpuset *cs, 


	if (cs->css.cgroup->nr_populated_csets)

		return true;

	if (!excluded_child && !cs->nr_subparts)

		return cgroup_is_populated(cs->css.cgroup);



	rcu_read_lock();

	cpuset_for_each_child(child, css, cs) {
@@ -1302,7 +1305,6 @@ static void reset_partition_data(struct cpuset *cs) 


	lockdep_assert_held(&callback_lock);



	cs->nr_subparts = 0;

	if (cpumask_empty(cs->exclusive_cpus)) {

		cpumask_clear(cs->effective_xcpus);

		if (is_cpu_exclusive(cs))
@@ -1746,7 +1748,6 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd, 
	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;

	int isolcpus_updated = 0;

	struct cpumask *xcpus = user_xcpus(cs);

	bool nocpu;
@@ -1771,10 +1772,9 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd, 
		if (is_partition_valid(parent))

			adding = cpumask_and(tmp->addmask,

					     xcpus, parent->effective_xcpus);

		if (old_prs > 0) {

		if (old_prs > 0)

			new_prs = -old_prs;

			subparts_delta--;

		}



		goto write_error;

	}
@@ -1829,7 +1829,6 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd, 
		WARN_ON_ONCE(!cpumask_subset(tmp->new_cpus, parent->effective_cpus));



		deleting = true;

		subparts_delta++;

	} else if (cmd == partcmd_disable) {

		/*

		 * May need to add cpus back to parent's effective_cpus
@@ -1840,7 +1839,6 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd, 
		if (is_partition_valid(cs)) {

			cpumask_copy(tmp->addmask, cs->effective_xcpus);

			adding = true;

			subparts_delta--;

		}

		new_prs = PRS_MEMBER;

	} else if (newmask) {
@@ -1963,17 +1961,13 @@ static int update_parent_effective_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;

		}

	}
@@ -2002,11 +1996,9 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd, 
	 * newly deleted ones will be added back to effective_cpus.

	 */

	spin_lock_irq(&callback_lock);

	if (old_prs != new_prs) {

	if (old_prs != new_prs)

		cs->partition_root_state = new_prs;

		if (new_prs <= 0)

			cs->nr_subparts = 0;

	}



	/*

	 * Adding to parent's effective_cpus means deletion CPUs from cs

	 * and vice versa.
@@ -2018,10 +2010,6 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd, 
		isolcpus_updated += partition_xcpus_add(new_prs, parent,

							tmp->delmask);



	if (is_partition_valid(parent)) {

		parent->nr_subparts += subparts_delta;

		WARN_ON_ONCE(parent->nr_subparts < 0);

	}

	spin_unlock_irq(&callback_lock);

	update_unbound_workqueue_cpumask(isolcpus_updated);
@@ -2105,8 +2093,6 @@ static void compute_partition_effective_cpumask(struct cpuset *cs, 
			 */

			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;
@@ -4021,7 +4007,6 @@ static void cpuset_handle_hotplug(void) 
		 */

		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,