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Subject[PATCH RT 5/8] sched/deadline: Reclaim cpuset bandwidth in .migrate_task_rq()
Date
With the changes to migrate disabling, ->set_cpus_allowed() no longer
gets deferred until migrate_enable(). To avoid releasing the bandwidth
while the task may still be executing on the old CPU, move the subtraction
to ->migrate_task_rq().

Signed-off-by: Scott Wood <swood@redhat.com>
---
kernel/sched/deadline.c | 67 +++++++++++++++++++++++--------------------------
1 file changed, 31 insertions(+), 36 deletions(-)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index c18be51f7608..2f18d0cf1b56 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1606,14 +1606,42 @@ static void yield_task_dl(struct rq *rq)
return cpu;
}

+static void free_old_cpuset_bw_dl(struct rq *rq, struct task_struct *p)
+{
+ struct root_domain *src_rd = rq->rd;
+
+ /*
+ * Migrating a SCHED_DEADLINE task between exclusive
+ * cpusets (different root_domains) entails a bandwidth
+ * update. We already made space for us in the destination
+ * domain (see cpuset_can_attach()).
+ */
+ if (!cpumask_intersects(src_rd->span, p->cpus_ptr)) {
+ struct dl_bw *src_dl_b;
+
+ src_dl_b = dl_bw_of(cpu_of(rq));
+ /*
+ * We now free resources of the root_domain we are migrating
+ * off. In the worst case, sched_setattr() may temporary fail
+ * until we complete the update.
+ */
+ raw_spin_lock(&src_dl_b->lock);
+ __dl_sub(src_dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p)));
+ raw_spin_unlock(&src_dl_b->lock);
+ }
+}
+
static void migrate_task_rq_dl(struct task_struct *p, int new_cpu __maybe_unused)
{
struct rq *rq;

- if (p->state != TASK_WAKING)
+ rq = task_rq(p);
+
+ if (p->state != TASK_WAKING) {
+ free_old_cpuset_bw_dl(rq, p);
return;
+ }

- rq = task_rq(p);
/*
* Since p->state == TASK_WAKING, set_task_cpu() has been called
* from try_to_wake_up(). Hence, p->pi_lock is locked, but
@@ -2220,39 +2248,6 @@ static void task_woken_dl(struct rq *rq, struct task_struct *p)
}
}

-static void set_cpus_allowed_dl(struct task_struct *p,
- const struct cpumask *new_mask)
-{
- struct root_domain *src_rd;
- struct rq *rq;
-
- BUG_ON(!dl_task(p));
-
- rq = task_rq(p);
- src_rd = rq->rd;
- /*
- * Migrating a SCHED_DEADLINE task between exclusive
- * cpusets (different root_domains) entails a bandwidth
- * update. We already made space for us in the destination
- * domain (see cpuset_can_attach()).
- */
- if (!cpumask_intersects(src_rd->span, new_mask)) {
- struct dl_bw *src_dl_b;
-
- src_dl_b = dl_bw_of(cpu_of(rq));
- /*
- * We now free resources of the root_domain we are migrating
- * off. In the worst case, sched_setattr() may temporary fail
- * until we complete the update.
- */
- raw_spin_lock(&src_dl_b->lock);
- __dl_sub(src_dl_b, p->dl.dl_bw, dl_bw_cpus(task_cpu(p)));
- raw_spin_unlock(&src_dl_b->lock);
- }
-
- set_cpus_allowed_common(p, new_mask);
-}
-
/* Assumes rq->lock is held */
static void rq_online_dl(struct rq *rq)
{
@@ -2407,7 +2402,7 @@ static void prio_changed_dl(struct rq *rq, struct task_struct *p,
#ifdef CONFIG_SMP
.select_task_rq = select_task_rq_dl,
.migrate_task_rq = migrate_task_rq_dl,
- .set_cpus_allowed = set_cpus_allowed_dl,
+ .set_cpus_allowed = set_cpus_allowed_common,
.rq_online = rq_online_dl,
.rq_offline = rq_offline_dl,
.task_woken = task_woken_dl,
--
1.8.3.1
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