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Subject[RFC 44/60] cosched: Perform various rq_of() adjustments in scheduler code
Date
The functions check_preempt_tick() and entity_tick() are executed by
the leader of the group. As such, we already hold the lock for the
per CPU runqueue. Thus, we can use the quick path to resched_curr().
Also, hrtimers are only used/active on per-CPU runqueues. So, use that.

The function __account_cfs_rq_runtime() is called via the enqueue
path, where we don't necessarily hold the per-CPU runqueue lock.
Take the long route though resched_curr().

The function list_add_leaf_cfs_rq() manages a supposedly depth
ordered list of CFS runqueues that contribute to the load on a certain
runqueue. This is used during load balancing. We keep these lists per
hierarchy level, which corresponds to the lock we hold and also
keeps the per-CPU logic compatible to what is there.

Signed-off-by: Jan H. Schönherr <jschoenh@amazon.de>
---
kernel/sched/fair.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index f55954e7cedc..fff88694560c 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -342,7 +342,7 @@ static inline struct cfs_rq *parent_cfs_rq(struct cfs_rq *cfs_rq)
static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
{
if (!cfs_rq->on_list) {
- struct rq *rq = rq_of(cfs_rq);
+ struct rq *rq = hrq_of(cfs_rq);
struct cfs_rq *pcfs_rq = parent_cfs_rq(cfs_rq);
/*
* Ensure we either appear before our parent (if already
@@ -4072,7 +4072,7 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
ideal_runtime = sched_slice(cfs_rq, curr);
delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
if (delta_exec > ideal_runtime) {
- resched_curr(rq_of(cfs_rq));
+ resched_curr(cpu_rq_of(cfs_rq));
/*
* The current task ran long enough, ensure it doesn't get
* re-elected due to buddy favours.
@@ -4096,7 +4096,7 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
return;

if (delta > ideal_runtime)
- resched_curr(rq_of(cfs_rq));
+ resched_curr(cpu_rq_of(cfs_rq));
}

static void
@@ -4238,14 +4238,14 @@ entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
* validating it and just reschedule.
*/
if (queued) {
- resched_curr(rq_of(cfs_rq));
+ resched_curr(cpu_rq_of(cfs_rq));
return;
}
/*
* don't let the period tick interfere with the hrtick preemption
*/
if (!sched_feat(DOUBLE_TICK) &&
- hrtimer_active(&rq_of(cfs_rq)->hrtick_timer))
+ hrtimer_active(&cpu_rq_of(cfs_rq)->hrtick_timer))
return;
#endif

@@ -4422,7 +4422,7 @@ static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec)
* hierarchy can be throttled
*/
if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr))
- resched_curr(rq_of(cfs_rq));
+ resched_curr(hrq_of(cfs_rq));
}

static __always_inline
--
2.9.3.1.gcba166c.dirty
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