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Subject[RFC 39/60] cosched: Adjust task group management for hierarchical runqueues
Date
Provide variants of the task group CFS traversal constructs that also
reach the hierarchical runqueues. Adjust task group management functions
where necessary.

The most changes are in alloc_fair_sched_group(), where we now need to
be a bit more careful during initialization.

Signed-off-by: Jan H. Schönherr <jschoenh@amazon.de>
---
kernel/sched/cosched.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++
kernel/sched/fair.c | 47 ++++++++++++++++++++++++++++------
kernel/sched/sched.h | 17 +++++++++++++
3 files changed, 124 insertions(+), 8 deletions(-)

diff --git a/kernel/sched/cosched.c b/kernel/sched/cosched.c
index 48394050ec34..b897319d046c 100644
--- a/kernel/sched/cosched.c
+++ b/kernel/sched/cosched.c
@@ -10,6 +10,63 @@

#include "sched.h"

+/*****************************************************************************
+ * Task group traversal
+ *****************************************************************************/
+
+static struct sdrq *leftmost_sdrq(struct sdrq *sdrq)
+{
+ while (!list_empty(&sdrq->children))
+ sdrq = list_first_entry(&sdrq->children, struct sdrq, siblings);
+ return sdrq;
+}
+
+struct cfs_rq *taskgroup_first_cfsrq(struct task_group *tg)
+{
+ if (!tg->top_cfsrq)
+ return NULL;
+ return leftmost_sdrq(&tg->top_cfsrq->sdrq)->cfs_rq;
+}
+
+struct cfs_rq *taskgroup_next_cfsrq(struct task_group *tg, struct cfs_rq *cfs)
+{
+ struct sdrq *sdrq = &cfs->sdrq;
+ struct sdrq *parent = sdrq->sd_parent;
+
+ if (cfs == tg->top_cfsrq)
+ return NULL;
+
+ list_for_each_entry_continue(sdrq, &parent->children, siblings)
+ return leftmost_sdrq(sdrq)->cfs_rq;
+
+ return parent->cfs_rq;
+}
+
+struct cfs_rq *taskgroup_first_cfsrq_topdown(struct task_group *tg)
+{
+ return tg->top_cfsrq;
+}
+
+struct cfs_rq *taskgroup_next_cfsrq_topdown(struct task_group *tg,
+ struct cfs_rq *cfs)
+{
+ struct sdrq *sdrq = &cfs->sdrq;
+ struct sdrq *parent = sdrq->sd_parent;
+
+ if (!list_empty(&sdrq->children)) {
+ sdrq = list_first_entry(&sdrq->children, struct sdrq, siblings);
+ return sdrq->cfs_rq;
+ }
+
+ while (sdrq != &tg->top_cfsrq->sdrq) {
+ list_for_each_entry_continue(sdrq, &parent->children, siblings)
+ return sdrq->cfs_rq;
+ sdrq = parent;
+ parent = sdrq->sd_parent;
+ }
+ return NULL;
+}
+
static int mask_to_node(const struct cpumask *span)
{
int node = cpu_to_node(cpumask_first(span));
@@ -427,3 +484,14 @@ void cosched_init_hierarchy(void)
list_add_tail(&sdrq->siblings, &sdrq->sd_parent->children);
}
}
+
+/*****************************************************************************
+ * Task group management functions
+ *****************************************************************************/
+
+void cosched_init_sdrq(struct task_group *tg, struct cfs_rq *cfs_rq,
+ struct cfs_rq *sd_parent, struct cfs_rq *tg_parent)
+{
+ init_sdrq(tg, &cfs_rq->sdrq, sd_parent ? &sd_parent->sdrq : NULL,
+ &tg_parent->sdrq, tg_parent->sdrq.data);
+}
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 33e3f759eb99..f72a72c8c3b8 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -9895,10 +9895,29 @@ void free_fair_sched_group(struct task_group *tg)
kfree(tg->cfs_rq);
}

+#ifdef CONFIG_COSCHEDULING
+static struct cfs_rq *find_sd_parent(struct cfs_rq *sd_parent,
+ struct cfs_rq *tg_parent)
+{
+ if (!sd_parent)
+ return NULL;
+
+ while (sd_parent->sdrq.tg_parent != tg_parent->sdrq.sd_parent)
+ sd_parent = sd_parent->sdrq.sd_parent->cfs_rq;
+ return sd_parent;
+}
+#else
+static struct cfs_rq *find_sd_parent(struct cfs_rq *sd_parent,
+ struct cfs_rq *tg_parent)
+{
+ return NULL;
+}
+#endif
+
int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
{
struct sched_entity *se;
- struct cfs_rq *cfs_rq, *pcfs_rq;
+ struct cfs_rq *cfs_rq = NULL, *pcfs_rq;

tg->cfs_rq = kcalloc(nr_cpu_ids, sizeof(cfs_rq), GFP_KERNEL);
if (!tg->cfs_rq)
@@ -9908,18 +9927,30 @@ int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)

init_cfs_bandwidth(tg_cfs_bandwidth(tg));

- taskgroup_for_each_cfsrq(parent, pcfs_rq) {
- struct rq *rq = rq_of(pcfs_rq);
- int node = cpu_to_node(cpu_of(rq));
+#ifdef CONFIG_COSCHEDULING
+ raw_spin_lock_init(&tg->lock);
+#endif
+
+ taskgroup_for_each_cfsrq_topdown(parent, pcfs_rq) {
+ struct rq *rq = hrq_of(pcfs_rq);
+ int node = node_of(rq);
+ struct cfs_rq *sdcfs_rq = find_sd_parent(cfs_rq, pcfs_rq);

cfs_rq = kzalloc_node(sizeof(*cfs_rq), GFP_KERNEL, node);
se = kzalloc_node(sizeof(*se), GFP_KERNEL, node);
if (!cfs_rq || !se)
goto err_free;

- tg->cfs_rq[cpu_of(rq)] = cfs_rq;
+#ifdef CONFIG_COSCHEDULING
+ if (!sdcfs_rq)
+ tg->top_cfsrq = cfs_rq;
+#endif
+ if (is_cpu_rq(rq))
+ tg->cfs_rq[cpu_of(rq)] = cfs_rq;
+
init_cfs_rq(cfs_rq);
init_tg_cfs_entry(tg, cfs_rq, se, rq, pcfs_rq);
+ cosched_init_sdrq(tg, cfs_rq, sdcfs_rq, pcfs_rq);
}

return 1;
@@ -9938,7 +9969,7 @@ void online_fair_sched_group(struct task_group *tg)
struct rq *rq;

taskgroup_for_each_cfsrq(tg, cfs) {
- rq = rq_of(cfs);
+ rq = hrq_of(cfs);
se = cfs->my_se;

raw_spin_lock_irq(&rq->lock);
@@ -9964,9 +9995,9 @@ void unregister_fair_sched_group(struct task_group *tg)
if (!cfs->on_list)
continue;

- raw_spin_lock_irqsave(&rq_of(cfs)->lock, flags);
+ raw_spin_lock_irqsave(&hrq_of(cfs)->lock, flags);
list_del_leaf_cfs_rq(cfs);
- raw_spin_unlock_irqrestore(&rq_of(cfs)->lock, flags);
+ raw_spin_unlock_irqrestore(&hrq_of(cfs)->lock, flags);
}
}

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index bc3631b8b955..38b4500095ca 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1109,6 +1109,17 @@ static inline int cpu_of(struct rq *rq)
(cfs) = (ncfs), \
(ncfs) = (cfs) ? taskgroup_next_cfsrq(tg, cfs) : NULL)

+#ifdef CONFIG_COSCHEDULING
+#define taskgroup_for_each_cfsrq_topdown(tg, cfs) \
+ for ((cfs) = taskgroup_first_cfsrq_topdown(tg); (cfs); \
+ (cfs) = taskgroup_next_cfsrq_topdown(tg, cfs))
+struct cfs_rq *taskgroup_first_cfsrq(struct task_group *tg);
+struct cfs_rq *taskgroup_next_cfsrq(struct task_group *tg, struct cfs_rq *cfs);
+struct cfs_rq *taskgroup_first_cfsrq_topdown(struct task_group *tg);
+struct cfs_rq *taskgroup_next_cfsrq_topdown(struct task_group *tg,
+ struct cfs_rq *cfs);
+#else /* !CONFIG_COSCHEDULING */
+#define taskgroup_for_each_cfsrq_topdown taskgroup_for_each_cfsrq
static inline struct cfs_rq *taskgroup_first_cfsrq(struct task_group *tg)
{
int cpu = cpumask_first(cpu_possible_mask);
@@ -1127,6 +1138,7 @@ static inline struct cfs_rq *taskgroup_next_cfsrq(struct task_group *tg,
return NULL;
return tg->cfs_rq[cpu];
}
+#endif /* !CONFIG_COSCHEDULING */
#endif /* CONFIG_FAIR_GROUP_SCHED */

#ifdef CONFIG_COSCHEDULING
@@ -1181,10 +1193,15 @@ static inline bool is_sd_se(struct sched_entity *se)
void cosched_init_bottom(void);
void cosched_init_topology(void);
void cosched_init_hierarchy(void);
+void cosched_init_sdrq(struct task_group *tg, struct cfs_rq *cfs,
+ struct cfs_rq *sd_parent, struct cfs_rq *tg_parent);
#else /* !CONFIG_COSCHEDULING */
static inline void cosched_init_bottom(void) { }
static inline void cosched_init_topology(void) { }
static inline void cosched_init_hierarchy(void) { }
+static inline void cosched_init_sdrq(struct task_group *tg, struct cfs_rq *cfs,
+ struct cfs_rq *sd_parent,
+ struct cfs_rq *tg_parent) { }
#endif /* !CONFIG_COSCHEDULING */

#ifdef CONFIG_SCHED_SMT
--
2.9.3.1.gcba166c.dirty
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