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cpuset: introduce effective_{cpumask|nodemask}_cpuset() 

effective_cpumask_cpuset() returns an ancestor cpuset which has
non-empty cpumask.

If a cpuset is empty and the tasks in it need to update their
cpus_allowed, they take on the ancestor cpuset's cpumask.

This currently won't change any behavior, but it will later allow us
to keep tasks in empty cpusets.

Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Li Zefan 2013-06-09 17:15:22 +08:00 committed by Tejun Heo
parent 33ad801dfb
commit 070b57fcac
1 changed files with 65 additions and 11 deletions
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76
kernel/cpuset.c
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@ -791,6 +791,45 @@ void rebuild_sched_domains(void)
mutex_unlock(&cpuset_mutex);
}
/*
* effective_cpumask_cpuset - return nearest ancestor with non-empty cpus
* @cs: the cpuset in interest
*
* A cpuset's effective cpumask is the cpumask of the nearest ancestor
* with non-empty cpus. We use effective cpumask whenever:
* - we update tasks' cpus_allowed. (they take on the ancestor's cpumask
* if the cpuset they reside in has no cpus)
* - we want to retrieve task_cs(tsk)'s cpus_allowed.
*
* Called with cpuset_mutex held. cpuset_cpus_allowed_fallback() is an
* exception. See comments there.
*/
static struct cpuset *effective_cpumask_cpuset(struct cpuset *cs)
{
while (cpumask_empty(cs->cpus_allowed))
cs = parent_cs(cs);
return cs;
}
/*
* effective_nodemask_cpuset - return nearest ancestor with non-empty mems
* @cs: the cpuset in interest
*
* A cpuset's effective nodemask is the nodemask of the nearest ancestor
* with non-empty memss. We use effective nodemask whenever:
* - we update tasks' mems_allowed. (they take on the ancestor's nodemask
* if the cpuset they reside in has no mems)
* - we want to retrieve task_cs(tsk)'s mems_allowed.
*
* Called with cpuset_mutex held.
*/
static struct cpuset *effective_nodemask_cpuset(struct cpuset *cs)
{
while (nodes_empty(cs->mems_allowed))
cs = parent_cs(cs);
return cs;
}
/**
* cpuset_change_cpumask - make a task's cpus_allowed the same as its cpuset's
* @tsk: task to test
@ -805,7 +844,10 @@ void rebuild_sched_domains(void)
static void cpuset_change_cpumask(struct task_struct *tsk,
struct cgroup_scanner *scan)
{
set_cpus_allowed_ptr(tsk, ((cgroup_cs(scan->cg))->cpus_allowed));
struct cpuset *cpus_cs;
cpus_cs = effective_cpumask_cpuset(cgroup_cs(scan->cg));
set_cpus_allowed_ptr(tsk, cpus_cs->cpus_allowed);
}
/**
@ -920,12 +962,14 @@ static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
const nodemask_t *to)
{
struct task_struct *tsk = current;
struct cpuset *mems_cs;
tsk->mems_allowed = *to;
do_migrate_pages(mm, from, to, MPOL_MF_MOVE_ALL);
guarantee_online_mems(task_cs(tsk),&tsk->mems_allowed);
mems_cs = effective_nodemask_cpuset(task_cs(tsk));
guarantee_online_mems(mems_cs, &tsk->mems_allowed);
}
/*
@ -1018,10 +1062,11 @@ static void update_tasks_nodemask(struct cpuset *cs, struct ptr_heap *heap)
{
static nodemask_t newmems; /* protected by cpuset_mutex */
struct cgroup_scanner scan;
struct cpuset *mems_cs = effective_nodemask_cpuset(cs);
cpuset_being_rebound = cs; /* causes mpol_dup() rebind */
guarantee_online_mems(cs, &newmems);
guarantee_online_mems(mems_cs, &newmems);
scan.cg = cs->css.cgroup;
scan.test_task = NULL;
@ -1405,6 +1450,8 @@ static void cpuset_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
struct cgroup *oldcgrp = cgroup_taskset_cur_cgroup(tset);
struct cpuset *cs = cgroup_cs(cgrp);
struct cpuset *oldcs = cgroup_cs(oldcgrp);
struct cpuset *cpus_cs = effective_cpumask_cpuset(cs);
struct cpuset *mems_cs = effective_nodemask_cpuset(cs);
mutex_lock(&cpuset_mutex);
@ -1412,9 +1459,9 @@ static void cpuset_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
if (cs == &top_cpuset)
cpumask_copy(cpus_attach, cpu_possible_mask);
else
guarantee_online_cpus(cs, cpus_attach);
guarantee_online_cpus(cpus_cs, cpus_attach);
guarantee_online_mems(cs, &cpuset_attach_nodemask_to);
guarantee_online_mems(mems_cs, &cpuset_attach_nodemask_to);
cgroup_taskset_for_each(task, cgrp, tset) {
/*
@ -1434,9 +1481,11 @@ static void cpuset_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
cpuset_attach_nodemask_to = cs->mems_allowed;
mm = get_task_mm(leader);
if (mm) {
struct cpuset *mems_oldcs = effective_nodemask_cpuset(oldcs);
mpol_rebind_mm(mm, &cpuset_attach_nodemask_to);
if (is_memory_migrate(cs))
cpuset_migrate_mm(mm, &oldcs->mems_allowed,
cpuset_migrate_mm(mm, &mems_oldcs->mems_allowed,
&cpuset_attach_nodemask_to);
mmput(mm);
}
@ -2186,20 +2235,23 @@ void __init cpuset_init_smp(void)
void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
{
struct cpuset *cpus_cs;
mutex_lock(&callback_mutex);
task_lock(tsk);
guarantee_online_cpus(task_cs(tsk), pmask);
cpus_cs = effective_cpumask_cpuset(task_cs(tsk));
guarantee_online_cpus(cpus_cs, pmask);
task_unlock(tsk);
mutex_unlock(&callback_mutex);
}
void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
{
const struct cpuset *cs;
const struct cpuset *cpus_cs;
rcu_read_lock();
cs = task_cs(tsk);
do_set_cpus_allowed(tsk, cs->cpus_allowed);
cpus_cs = effective_cpumask_cpuset(task_cs(tsk));
do_set_cpus_allowed(tsk, cpus_cs->cpus_allowed);
rcu_read_unlock();
/*
@ -2238,11 +2290,13 @@ void cpuset_init_current_mems_allowed(void)
nodemask_t cpuset_mems_allowed(struct task_struct *tsk)
{
struct cpuset *mems_cs;
nodemask_t mask;
mutex_lock(&callback_mutex);
task_lock(tsk);
guarantee_online_mems(task_cs(tsk), &mask);
mems_cs = effective_nodemask_cpuset(task_cs(tsk));
guarantee_online_mems(mems_cs, &mask);
task_unlock(tsk);
mutex_unlock(&callback_mutex);