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Message-ID: <20250731105543.40832-13-yurand2000@gmail.com>
Date: Thu, 31 Jul 2025 12:55:30 +0200
From: Yuri Andriaccio <yurand2000@...il.com>
To: Ingo Molnar <mingo@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Juri Lelli <juri.lelli@...hat.com>,
Vincent Guittot <vincent.guittot@...aro.org>,
Dietmar Eggemann <dietmar.eggemann@....com>,
Steven Rostedt <rostedt@...dmis.org>,
Ben Segall <bsegall@...gle.com>,
Mel Gorman <mgorman@...e.de>,
Valentin Schneider <vschneid@...hat.com>
Cc: linux-kernel@...r.kernel.org,
Luca Abeni <luca.abeni@...tannapisa.it>,
Yuri Andriaccio <yuri.andriaccio@...tannapisa.it>
Subject: [RFC PATCH v2 12/25] sched/rt: Add {alloc/free}_rt_sched_group and dl_server specific functions
From: luca abeni <luca.abeni@...tannapisa.it>
Add allocation and deallocation code for rt-cgroups. Add rt dl_server's specific
functions that pick the next eligible task to run.
Co-developed-by: Alessio Balsini <a.balsini@...up.it>
Signed-off-by: Alessio Balsini <a.balsini@...up.it>
Co-developed-by: Andrea Parri <parri.andrea@...il.com>
Signed-off-by: Andrea Parri <parri.andrea@...il.com>
Co-developed-by: Yuri Andriaccio <yurand2000@...il.com>
Signed-off-by: Yuri Andriaccio <yurand2000@...il.com>
Signed-off-by: luca abeni <luca.abeni@...tannapisa.it>
---
kernel/sched/rt.c | 107 ++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 104 insertions(+), 3 deletions(-)
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 38178003184..9c4ac6875a2 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -93,8 +93,39 @@ void unregister_rt_sched_group(struct task_group *tg)
void free_rt_sched_group(struct task_group *tg)
{
+ int i;
+
if (!rt_group_sched_enabled())
return;
+
+ for_each_possible_cpu(i) {
+ if (tg->dl_se) {
+ unsigned long flags;
+
+ /*
+ * Since the dl timer is going to be cancelled,
+ * we risk to never decrease the running bw...
+ * Fix this issue by changing the group runtime
+ * to 0 immediately before freeing it.
+ */
+ dl_init_tg(tg->dl_se[i], 0, tg->dl_se[i]->dl_period);
+ raw_spin_rq_lock_irqsave(cpu_rq(i), flags);
+ BUG_ON(tg->rt_rq[i]->rt_nr_running);
+ raw_spin_rq_unlock_irqrestore(cpu_rq(i), flags);
+
+ hrtimer_cancel(&tg->dl_se[i]->dl_timer);
+ kfree(tg->dl_se[i]);
+ }
+ if (tg->rt_rq) {
+ struct rq *served_rq;
+
+ served_rq = container_of(tg->rt_rq[i], struct rq, rt);
+ kfree(served_rq);
+ }
+ }
+
+ kfree(tg->rt_rq);
+ kfree(tg->dl_se);
}
void init_tg_rt_entry(struct task_group *tg, struct rq *served_rq,
@@ -109,12 +140,77 @@ void init_tg_rt_entry(struct task_group *tg, struct rq *served_rq,
tg->dl_se[cpu] = dl_se;
}
+static bool rt_server_has_tasks(struct sched_dl_entity *dl_se)
+{
+ return !!dl_se->my_q->rt.rt_nr_running;
+}
+
+static struct task_struct *_pick_next_task_rt(struct rt_rq *rt_rq);
+static inline void set_next_task_rt(struct rq *rq, struct task_struct *p, bool first);
+static struct task_struct *rt_server_pick(struct sched_dl_entity *dl_se)
+{
+ struct rt_rq *rt_rq = &dl_se->my_q->rt;
+ struct rq *rq = rq_of_rt_rq(rt_rq);
+ struct task_struct *p;
+
+ if (dl_se->my_q->rt.rt_nr_running == 0)
+ return NULL;
+
+ p = _pick_next_task_rt(rt_rq);
+ set_next_task_rt(rq, p, true);
+
+ return p;
+}
+
int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
{
+ struct rq *s_rq;
+ struct sched_dl_entity *dl_se;
+ int i;
+
if (!rt_group_sched_enabled())
return 1;
+ tg->rt_rq = kcalloc(nr_cpu_ids, sizeof(struct rt_rq *), GFP_KERNEL);
+ if (!tg->rt_rq)
+ goto err;
+ tg->dl_se = kcalloc(nr_cpu_ids, sizeof(dl_se), GFP_KERNEL);
+ if (!tg->dl_se)
+ goto err;
+
+ init_dl_bandwidth(&tg->dl_bandwidth, 0, 0);
+
+ for_each_possible_cpu(i) {
+ s_rq = kzalloc_node(sizeof(struct rq),
+ GFP_KERNEL, cpu_to_node(i));
+ if (!s_rq)
+ goto err;
+
+ dl_se = kzalloc_node(sizeof(struct sched_dl_entity),
+ GFP_KERNEL, cpu_to_node(i));
+ if (!dl_se)
+ goto err_free_rq;
+
+ init_rt_rq(&s_rq->rt);
+ init_dl_entity(dl_se);
+ dl_se->dl_runtime = tg->dl_bandwidth.dl_runtime;
+ dl_se->dl_period = tg->dl_bandwidth.dl_period;
+ dl_se->dl_deadline = dl_se->dl_period;
+ dl_se->dl_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime);
+ dl_se->dl_density = to_ratio(dl_se->dl_period, dl_se->dl_runtime);
+ dl_se->dl_server = 1;
+
+ dl_server_init(dl_se, &cpu_rq(i)->dl, s_rq, rt_server_has_tasks, rt_server_pick);
+
+ init_tg_rt_entry(tg, s_rq, dl_se, i, parent->dl_se[i]);
+ }
+
return 1;
+
+err_free_rq:
+ kfree(s_rq);
+err:
+ return 0;
}
#else /* !CONFIG_RT_GROUP_SCHED: */
@@ -860,9 +956,14 @@ static struct sched_rt_entity *pick_next_rt_entity(struct rt_rq *rt_rq)
return next;
}
-static struct task_struct *_pick_next_task_rt(struct rq *rq)
+static struct task_struct *_pick_next_task_rt(struct rt_rq *rt_rq)
{
- return NULL;
+ struct sched_rt_entity *rt_se;
+
+ rt_se = pick_next_rt_entity(rt_rq);
+ BUG_ON(!rt_se);
+
+ return rt_task_of(rt_se);
}
static struct task_struct *pick_task_rt(struct rq *rq)
@@ -872,7 +973,7 @@ static struct task_struct *pick_task_rt(struct rq *rq)
if (!sched_rt_runnable(rq))
return NULL;
- p = _pick_next_task_rt(rq);
+ p = _pick_next_task_rt(&rq->rt);
return p;
}
--
2.50.1
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