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sched/deadline: Merge dl_task_can_attach() and dl_cpu_busy() 

Both functions are doing almost the same, that is checking if admission
control is still respected.

With exclusive cpusets, dl_task_can_attach() checks if the destination
cpuset (i.e. its root domain) has enough CPU capacity to accommodate the
task.
dl_cpu_busy() checks if there is enough CPU capacity in the cpuset in
case the CPU is hot-plugged out.

dl_task_can_attach() is used to check if a task can be admitted while
dl_cpu_busy() is used to check if a CPU can be hotplugged out.

Make dl_cpu_busy() able to deal with a task and use it instead of
dl_task_can_attach() in task_can_attach().

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lore.kernel.org/r/20220302183433.333029-4-dietmar.eggemann@arm.com
This commit is contained in:
Dietmar Eggemann 2022-03-02 19:34:30 +01:00 committed by Peter Zijlstra
parent f1304ecbef
commit 772b6539fd
3 changed files with 24 additions and 44 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
kernel/sched/core.c
View File

@ -8805,8 +8805,11 @@ int task_can_attach(struct task_struct *p,
}
if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span,
cs_cpus_allowed))
ret = dl_task_can_attach(p, cs_cpus_allowed);
cs_cpus_allowed)) {
int cpu = cpumask_any_and(cpu_active_mask, cs_cpus_allowed);
ret = dl_cpu_busy(cpu, p);
}
out:
return ret;
@ -9090,8 +9093,10 @@ static void cpuset_cpu_active(void)
static int cpuset_cpu_inactive(unsigned int cpu)
{
if (!cpuhp_tasks_frozen) {
if (dl_cpu_busy(cpu))
return -EBUSY;
int ret = dl_cpu_busy(cpu, NULL);
if (ret)
return ret;
cpuset_update_active_cpus();
} else {
num_cpus_frozen++;

52
kernel/sched/deadline.c
View File

@ -2992,41 +2992,6 @@ bool dl_param_changed(struct task_struct *p, const struct sched_attr *attr)
}
#ifdef CONFIG_SMP
int dl_task_can_attach(struct task_struct *p, const struct cpumask *cs_cpus_allowed)
{
unsigned long flags, cap;
unsigned int dest_cpu;
struct dl_bw *dl_b;
bool overflow;
int ret;
dest_cpu = cpumask_any_and(cpu_active_mask, cs_cpus_allowed);
rcu_read_lock_sched();
dl_b = dl_bw_of(dest_cpu);
raw_spin_lock_irqsave(&dl_b->lock, flags);
cap = dl_bw_capacity(dest_cpu);
overflow = __dl_overflow(dl_b, cap, 0, p->dl.dl_bw);
if (overflow) {
ret = -EBUSY;
} else {
/*
* We reserve space for this task in the destination
* root_domain, as we can't fail after this point.
* We will free resources in the source root_domain
* later on (see set_cpus_allowed_dl()).
*/
int cpus = dl_bw_cpus(dest_cpu);
__dl_add(dl_b, p->dl.dl_bw, cpus);
ret = 0;
}
raw_spin_unlock_irqrestore(&dl_b->lock, flags);
rcu_read_unlock_sched();
return ret;
}
int dl_cpuset_cpumask_can_shrink(const struct cpumask *cur,
const struct cpumask *trial)
{
@ -3048,7 +3013,7 @@ int dl_cpuset_cpumask_can_shrink(const struct cpumask *cur,
return ret;
}
bool dl_cpu_busy(unsigned int cpu)
int dl_cpu_busy(int cpu, struct task_struct *p)
{
unsigned long flags, cap;
struct dl_bw *dl_b;
@ -3058,11 +3023,22 @@ bool dl_cpu_busy(unsigned int cpu)
dl_b = dl_bw_of(cpu);
raw_spin_lock_irqsave(&dl_b->lock, flags);
cap = dl_bw_capacity(cpu);
overflow = __dl_overflow(dl_b, cap, 0, 0);
overflow = __dl_overflow(dl_b, cap, 0, p ? p->dl.dl_bw : 0);
if (!overflow && p) {
/*
* We reserve space for this task in the destination
* root_domain, as we can't fail after this point.
* We will free resources in the source root_domain
* later on (see set_cpus_allowed_dl()).
*/
__dl_add(dl_b, p->dl.dl_bw, dl_bw_cpus(cpu));
}
raw_spin_unlock_irqrestore(&dl_b->lock, flags);
rcu_read_unlock_sched();
return overflow;
return overflow ? -EBUSY : 0;
}
#endif

3
kernel/sched/sched.h
View File

@ -324,9 +324,8 @@ extern void __setparam_dl(struct task_struct *p, const struct sched_attr *attr);
extern void __getparam_dl(struct task_struct *p, struct sched_attr *attr);
extern bool __checkparam_dl(const struct sched_attr *attr);
extern bool dl_param_changed(struct task_struct *p, const struct sched_attr *attr);
extern int dl_task_can_attach(struct task_struct *p, const struct cpumask *cs_cpus_allowed);
extern int dl_cpuset_cpumask_can_shrink(const struct cpumask *cur, const struct cpumask *trial);
extern bool dl_cpu_busy(unsigned int cpu);
extern int dl_cpu_busy(int cpu, struct task_struct *p);
#ifdef CONFIG_CGROUP_SCHED