Commit be4c9dd7 authored by Li Zefan's avatar Li Zefan Committed by Tejun Heo
Browse files

cpuset: enable onlined cpu/node in effective masks 



Firstly offline cpu1:

  # echo 0-1 > cpuset.cpus
  # echo 0 > /sys/devices/system/cpu/cpu1/online
  # cat cpuset.cpus
  0-1
  # cat cpuset.effective_cpus
  0

Then online it:

  # echo 1 > /sys/devices/system/cpu/cpu1/online
  # cat cpuset.cpus
  0-1
  # cat cpuset.effective_cpus
  0-1

And cpuset will bring it back to the effective mask.

The implementation is quite straightforward. Instead of calculating the
offlined cpus/mems and do updates, we just set the new effective_mask
to online_mask & congifured_mask.

This is a behavior change for default hierarchy, so legacy hierarchy
won't be affected.

v2:
- make refactoring of cpuset_hotplug_update_tasks() as seperate patch,
  suggested by Tejun.
- make hotplug_update_tasks_insane() use @new_cpus and @new_mems as
  hotplug_update_tasks_sane() does.

Signed-off-by: default avatarLi Zefan <lizefan@huawei.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 390a36aa

kernel/cpuset.c

+36 −29
Original line number Diff line number Diff line
@@ -2080,26 +2080,27 @@ static void remove_tasks_in_empty_cpuset(struct cpuset *cs) 
	}

}



static void hotplug_update_tasks_legacy(struct cpuset *cs,

					struct cpumask *off_cpus,

					nodemask_t *off_mems)

static void

hotplug_update_tasks_legacy(struct cpuset *cs,

			    struct cpumask *new_cpus, nodemask_t *new_mems,

			    bool cpus_updated, bool mems_updated)

{

	bool is_empty;



	mutex_lock(&callback_mutex);

	cpumask_andnot(cs->cpus_allowed, cs->cpus_allowed, off_cpus);

	cpumask_andnot(cs->effective_cpus, cs->effective_cpus, off_cpus);

	nodes_andnot(cs->mems_allowed, cs->mems_allowed, *off_mems);

	nodes_andnot(cs->effective_mems, cs->effective_mems, *off_mems);

	cpumask_copy(cs->cpus_allowed, new_cpus);

	cpumask_copy(cs->effective_cpus, new_cpus);

	cs->mems_allowed = *new_mems;

	cs->effective_mems = *new_mems;

	mutex_unlock(&callback_mutex);



	/*

	 * Don't call update_tasks_cpumask() if the cpuset becomes empty,

	 * as the tasks will be migratecd to an ancestor.

	 */

	if (!cpumask_empty(off_cpus) && !cpumask_empty(cs->cpus_allowed))

	if (cpus_updated && !cpumask_empty(cs->cpus_allowed))

		update_tasks_cpumask(cs);

	if (!nodes_empty(*off_mems) && !nodes_empty(cs->mems_allowed))

	if (mems_updated && !nodes_empty(cs->mems_allowed))

		update_tasks_nodemask(cs);



	is_empty = cpumask_empty(cs->cpus_allowed) ||
@@ -2118,24 +2119,24 @@ static void hotplug_update_tasks_legacy(struct cpuset *cs, 
	mutex_lock(&cpuset_mutex);

}



static void hotplug_update_tasks(struct cpuset *cs,

				 struct cpumask *off_cpus,

				 nodemask_t *off_mems)

static void

hotplug_update_tasks(struct cpuset *cs,

		     struct cpumask *new_cpus, nodemask_t *new_mems,

		     bool cpus_updated, bool mems_updated)

{

	if (cpumask_empty(new_cpus))

		cpumask_copy(new_cpus, parent_cs(cs)->effective_cpus);

	if (nodes_empty(*new_mems))

		*new_mems = parent_cs(cs)->effective_mems;



	mutex_lock(&callback_mutex);

	cpumask_andnot(cs->effective_cpus, cs->effective_cpus, off_cpus);

	if (cpumask_empty(cs->effective_cpus))

		cpumask_copy(cs->effective_cpus,

			     parent_cs(cs)->effective_cpus);



	nodes_andnot(cs->effective_mems, cs->effective_mems, *off_mems);

	if (nodes_empty(cs->effective_mems))

		cs->effective_mems = parent_cs(cs)->effective_mems;

	cpumask_copy(cs->effective_cpus, new_cpus);

	cs->effective_mems = *new_mems;

	mutex_unlock(&callback_mutex);



	if (!cpumask_empty(off_cpus))

	if (cpus_updated)

		update_tasks_cpumask(cs);

	if (!nodes_empty(*off_mems))

	if (mems_updated)

		update_tasks_nodemask(cs);

}
@@ -2149,8 +2150,10 @@ static void hotplug_update_tasks(struct cpuset *cs, 
 */

static void cpuset_hotplug_update_tasks(struct cpuset *cs)

{

	static cpumask_t off_cpus;

	static nodemask_t off_mems;

	static cpumask_t new_cpus;

	static nodemask_t new_mems;

	bool cpus_updated;

	bool mems_updated;

retry:

	wait_event(cpuset_attach_wq, cs->attach_in_progress == 0);
@@ -2165,14 +2168,18 @@ retry: 
		goto retry;

	}



	cpumask_andnot(&off_cpus, cs->effective_cpus,

		       top_cpuset.effective_cpus);

	nodes_andnot(off_mems, cs->effective_mems, top_cpuset.effective_mems);

	cpumask_and(&new_cpus, cs->cpus_allowed, parent_cs(cs)->effective_cpus);

	nodes_and(new_mems, cs->mems_allowed, parent_cs(cs)->effective_mems);



	cpus_updated = !cpumask_equal(&new_cpus, cs->effective_cpus);

	mems_updated = !nodes_equal(new_mems, cs->effective_mems);



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

		hotplug_update_tasks(cs, &off_cpus, &off_mems);

		hotplug_update_tasks(cs, &new_cpus, &new_mems,

				     cpus_updated, mems_updated);

	else

		hotplug_update_tasks_legacy(cs, &off_cpus, &off_mems);

		hotplug_update_tasks_legacy(cs, &new_cpus, &new_mems,

					    cpus_updated, mems_updated);



	mutex_unlock(&cpuset_mutex);

}

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