mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-10 20:44:09 +08:00
cpuset: Honour task_cpu_possible_mask() in guarantee_online_cpus()
Asymmetric systems may not offer the same level of userspace ISA support across all CPUs, meaning that some applications cannot be executed by some CPUs. As a concrete example, upcoming arm64 big.LITTLE designs do not feature support for 32-bit applications on both clusters. Modify guarantee_online_cpus() to take task_cpu_possible_mask() into account when trying to find a suitable set of online CPUs for a given task. This will avoid passing an invalid mask to set_cpus_allowed_ptr() during ->attach() and will subsequently allow the cpuset hierarchy to be taken into account when forcefully overriding the affinity mask for a task which requires migration to a compatible CPU. Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <Valentin.Schneider@arm.com> Link: https://lkml.kernel.org/r/20210730112443.23245-4-will@kernel.org
This commit is contained in:
parent
d4b96fb92a
commit
431c69fac0
@ -185,7 +185,7 @@ static inline void cpuset_read_unlock(void) { }
|
||||
static inline void cpuset_cpus_allowed(struct task_struct *p,
|
||||
struct cpumask *mask)
|
||||
{
|
||||
cpumask_copy(mask, cpu_possible_mask);
|
||||
cpumask_copy(mask, task_cpu_possible_mask(p));
|
||||
}
|
||||
|
||||
static inline void cpuset_cpus_allowed_fallback(struct task_struct *p)
|
||||
|
@ -372,18 +372,29 @@ static inline bool is_in_v2_mode(void)
|
||||
}
|
||||
|
||||
/*
|
||||
* Return in pmask the portion of a cpusets's cpus_allowed that
|
||||
* are online. If none are online, walk up the cpuset hierarchy
|
||||
* until we find one that does have some online cpus.
|
||||
* Return in pmask the portion of a task's cpusets's cpus_allowed that
|
||||
* are online and are capable of running the task. If none are found,
|
||||
* walk up the cpuset hierarchy until we find one that does have some
|
||||
* appropriate cpus.
|
||||
*
|
||||
* One way or another, we guarantee to return some non-empty subset
|
||||
* of cpu_online_mask.
|
||||
*
|
||||
* Call with callback_lock or cpuset_mutex held.
|
||||
*/
|
||||
static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask)
|
||||
static void guarantee_online_cpus(struct task_struct *tsk,
|
||||
struct cpumask *pmask)
|
||||
{
|
||||
while (!cpumask_intersects(cs->effective_cpus, cpu_online_mask)) {
|
||||
const struct cpumask *possible_mask = task_cpu_possible_mask(tsk);
|
||||
struct cpuset *cs;
|
||||
|
||||
if (WARN_ON(!cpumask_and(pmask, possible_mask, cpu_online_mask)))
|
||||
cpumask_copy(pmask, cpu_online_mask);
|
||||
|
||||
rcu_read_lock();
|
||||
cs = task_cs(tsk);
|
||||
|
||||
while (!cpumask_intersects(cs->effective_cpus, pmask)) {
|
||||
cs = parent_cs(cs);
|
||||
if (unlikely(!cs)) {
|
||||
/*
|
||||
@ -393,11 +404,13 @@ static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask)
|
||||
* cpuset's effective_cpus is on its way to be
|
||||
* identical to cpu_online_mask.
|
||||
*/
|
||||
cpumask_copy(pmask, cpu_online_mask);
|
||||
return;
|
||||
goto out_unlock;
|
||||
}
|
||||
}
|
||||
cpumask_and(pmask, cs->effective_cpus, cpu_online_mask);
|
||||
cpumask_and(pmask, pmask, cs->effective_cpus);
|
||||
|
||||
out_unlock:
|
||||
rcu_read_unlock();
|
||||
}
|
||||
|
||||
/*
|
||||
@ -2199,15 +2212,13 @@ static void cpuset_attach(struct cgroup_taskset *tset)
|
||||
|
||||
percpu_down_write(&cpuset_rwsem);
|
||||
|
||||
/* prepare for attach */
|
||||
if (cs == &top_cpuset)
|
||||
cpumask_copy(cpus_attach, cpu_possible_mask);
|
||||
else
|
||||
guarantee_online_cpus(cs, cpus_attach);
|
||||
|
||||
guarantee_online_mems(cs, &cpuset_attach_nodemask_to);
|
||||
|
||||
cgroup_taskset_for_each(task, css, tset) {
|
||||
if (cs != &top_cpuset)
|
||||
guarantee_online_cpus(task, cpus_attach);
|
||||
else
|
||||
cpumask_copy(cpus_attach, task_cpu_possible_mask(task));
|
||||
/*
|
||||
* can_attach beforehand should guarantee that this doesn't
|
||||
* fail. TODO: have a better way to handle failure here
|
||||
@ -3302,9 +3313,7 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
|
||||
unsigned long flags;
|
||||
|
||||
spin_lock_irqsave(&callback_lock, flags);
|
||||
rcu_read_lock();
|
||||
guarantee_online_cpus(task_cs(tsk), pmask);
|
||||
rcu_read_unlock();
|
||||
guarantee_online_cpus(tsk, pmask);
|
||||
spin_unlock_irqrestore(&callback_lock, flags);
|
||||
}
|
||||
|
||||
|
Loading…
Reference in New Issue
Block a user