xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Förgrening 0
Kod Ärenden Pull-förfrågningar Actions Packages Projekt Släpp Wiki Aktiviteter

sched/core: Provide a pointer to the valid CPU mask

Bläddra i källkod 
In commit:

  4b53a3412d ("sched/core: Remove the tsk_nr_cpus_allowed() wrapper")

the tsk_nr_cpus_allowed() wrapper was removed. There was not
much difference in !RT but in RT we used this to implement
migrate_disable(). Within a migrate_disable() section the CPU mask is
restricted to single CPU while the "normal" CPU mask remains untouched.

As an alternative implementation Ingo suggested to use:

	struct task_struct {
		const cpumask_t		*cpus_ptr;
		cpumask_t		cpus_mask;
        };
with
	t->cpus_ptr = &t->cpus_mask;

In -RT we then can switch the cpus_ptr to:

	t->cpus_ptr = &cpumask_of(task_cpu(p));

in a migration disabled region. The rules are simple:

 - Code that 'uses' ->cpus_allowed would use the pointer.
 - Code that 'modifies' ->cpus_allowed would use the direct mask.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190423142636.14347-1-bigeasy@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Sebastian Andrzej Siewior
2019-04-23 16:26:36 +02:00
committad av Ingo Molnar
förälder f2c7c76c5d
incheckning 3bd3706251
23 ändrade filer med 75 tillägg och 73 borttagningar
Download Patch File Download Diff File Expand all files Collapse all files

34
kernel/sched/fair.c
Visa fil

@@ -1621,7 +1621,7 @@ static void task_numa_compare(struct task_numa_env *env,
* be incurred if the tasks were swapped.
*/
/* Skip this swap candidate if cannot move to the source cpu */
if (!cpumask_test_cpu(env->src_cpu, &cur->cpus_allowed))
if (!cpumask_test_cpu(env->src_cpu, cur->cpus_ptr))
goto unlock;
/*
@@ -1718,7 +1718,7 @@ static void task_numa_find_cpu(struct task_numa_env *env,
for_each_cpu(cpu, cpumask_of_node(env->dst_nid)) {
/* Skip this CPU if the source task cannot migrate */
if (!cpumask_test_cpu(cpu, &env->p->cpus_allowed))
if (!cpumask_test_cpu(cpu, env->p->cpus_ptr))
continue;
env->dst_cpu = cpu;
@@ -5831,7 +5831,7 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p,
/* Skip over this group if it has no CPUs allowed */
if (!cpumask_intersects(sched_group_span(group),
&p->cpus_allowed))
p->cpus_ptr))
continue;
local_group = cpumask_test_cpu(this_cpu,
@@ -5963,7 +5963,7 @@ find_idlest_group_cpu(struct sched_group *group, struct task_struct *p, int this
return cpumask_first(sched_group_span(group));
/* Traverse only the allowed CPUs */
for_each_cpu_and(i, sched_group_span(group), &p->cpus_allowed) {
for_each_cpu_and(i, sched_group_span(group), p->cpus_ptr) {
if (available_idle_cpu(i)) {
struct rq *rq = cpu_rq(i);
struct cpuidle_state *idle = idle_get_state(rq);
@@ -6003,7 +6003,7 @@ static inline int find_idlest_cpu(struct sched_domain *sd, struct task_struct *p
{
int new_cpu = cpu;
if (!cpumask_intersects(sched_domain_span(sd), &p->cpus_allowed))
if (!cpumask_intersects(sched_domain_span(sd), p->cpus_ptr))
return prev_cpu;
/*
@@ -6120,7 +6120,7 @@ static int select_idle_core(struct task_struct *p, struct sched_domain *sd, int
if (!test_idle_cores(target, false))
return -1;
cpumask_and(cpus, sched_domain_span(sd), &p->cpus_allowed);
cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr);
for_each_cpu_wrap(core, cpus, target) {
bool idle = true;
@@ -6154,7 +6154,7 @@ static int select_idle_smt(struct task_struct *p, int target)
return -1;
for_each_cpu(cpu, cpu_smt_mask(target)) {
if (!cpumask_test_cpu(cpu, &p->cpus_allowed))
if (!cpumask_test_cpu(cpu, p->cpus_ptr))
continue;
if (available_idle_cpu(cpu))
return cpu;
@@ -6217,7 +6217,7 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t
for_each_cpu_wrap(cpu, sched_domain_span(sd), target) {
if (!--nr)
return -1;
if (!cpumask_test_cpu(cpu, &p->cpus_allowed))
if (!cpumask_test_cpu(cpu, p->cpus_ptr))
continue;
if (available_idle_cpu(cpu))
break;
@@ -6254,7 +6254,7 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target)
recent_used_cpu != target &&
cpus_share_cache(recent_used_cpu, target) &&
available_idle_cpu(recent_used_cpu) &&
cpumask_test_cpu(p->recent_used_cpu, &p->cpus_allowed)) {
cpumask_test_cpu(p->recent_used_cpu, p->cpus_ptr)) {
/*
* Replace recent_used_cpu with prev as it is a potential
* candidate for the next wake:
@@ -6600,7 +6600,7 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu)
int max_spare_cap_cpu = -1;
for_each_cpu_and(cpu, perf_domain_span(pd), sched_domain_span(sd)) {
if (!cpumask_test_cpu(cpu, &p->cpus_allowed))
if (!cpumask_test_cpu(cpu, p->cpus_ptr))
continue;
/* Skip CPUs that will be overutilized. */
@@ -6689,7 +6689,7 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f
}
want_affine = !wake_wide(p) && !wake_cap(p, cpu, prev_cpu) &&
cpumask_test_cpu(cpu, &p->cpus_allowed);
cpumask_test_cpu(cpu, p->cpus_ptr);
}
rcu_read_lock();
@@ -7445,14 +7445,14 @@ int can_migrate_task(struct task_struct *p, struct lb_env *env)
/*
* We do not migrate tasks that are:
* 1) throttled_lb_pair, or
* 2) cannot be migrated to this CPU due to cpus_allowed, or
* 2) cannot be migrated to this CPU due to cpus_ptr, or
* 3) running (obviously), or
* 4) are cache-hot on their current CPU.
*/
if (throttled_lb_pair(task_group(p), env->src_cpu, env->dst_cpu))
return 0;
if (!cpumask_test_cpu(env->dst_cpu, &p->cpus_allowed)) {
if (!cpumask_test_cpu(env->dst_cpu, p->cpus_ptr)) {
int cpu;
schedstat_inc(p->se.statistics.nr_failed_migrations_affine);
@@ -7472,7 +7472,7 @@ int can_migrate_task(struct task_struct *p, struct lb_env *env)
/* Prevent to re-select dst_cpu via env's CPUs: */
for_each_cpu_and(cpu, env->dst_grpmask, env->cpus) {
if (cpumask_test_cpu(cpu, &p->cpus_allowed)) {
if (cpumask_test_cpu(cpu, p->cpus_ptr)) {
env->flags |= LBF_DST_PINNED;
env->new_dst_cpu = cpu;
break;
@@ -8099,7 +8099,7 @@ static inline int check_misfit_status(struct rq *rq, struct sched_domain *sd)
/*
* Group imbalance indicates (and tries to solve) the problem where balancing
* groups is inadequate due to ->cpus_allowed constraints.
* groups is inadequate due to ->cpus_ptr constraints.
*
* Imagine a situation of two groups of 4 CPUs each and 4 tasks each with a
* cpumask covering 1 CPU of the first group and 3 CPUs of the second group.
@@ -8768,7 +8768,7 @@ static struct sched_group *find_busiest_group(struct lb_env *env)
/*
* If the busiest group is imbalanced the below checks don't
* work because they assume all things are equal, which typically
* isn't true due to cpus_allowed constraints and the like.
* isn't true due to cpus_ptr constraints and the like.
*/
if (busiest->group_type == group_imbalanced)
goto force_balance;
@@ -9210,7 +9210,7 @@ more_balance:
* if the curr task on busiest CPU can't be
* moved to this_cpu:
*/
if (!cpumask_test_cpu(this_cpu, &busiest->curr->cpus_allowed)) {
if (!cpumask_test_cpu(this_cpu, busiest->curr->cpus_ptr)) {
raw_spin_unlock_irqrestore(&busiest->lock,
flags);
env.flags |= LBF_ALL_PINNED;