[PATCH 6/8] Modify the curr/next priority tracking

From: Fabio Checconi
Date: Mon Jun 15 2009 - 15:08:02 EST


Synchronize with the data structures used for EDF throttling the code
which tracks the highest and the second-highest priority in each group.
---
kernel/sched_rt.c | 82 ++++++++++++++++++++++++++++++++++++++++------------
1 files changed, 63 insertions(+), 19 deletions(-)

diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 5d2353f..f43ce7b 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -536,16 +536,57 @@ static inline struct sched_rt_entity *__rt_edf_next(struct sched_rt_entity *se)

#if defined CONFIG_SMP

-static struct task_struct *pick_next_highest_task_rt(struct rq *rq, int cpu);
+static int is_task_rq(struct rt_rq *rt_rq)
+{
+ struct task_rt_group *rt_tg = rt_rq->rt_tg;
+ return rt_tg->tg == container_of(rt_tg, struct task_group,
+ rt_task_group);
+}

-static inline int next_prio(struct rq *rq)
+static void find_highest_prios(struct rt_rq *rt_rq, int *curr, int *next)
{
- struct task_struct *next = pick_next_highest_task_rt(rq, rq->cpu);
+ struct sched_rt_entity *se, *next_se;
+ struct rt_rq *child;
+ struct rb_node *node;
+ int curp = MAX_RT_PRIO, nextp = MAX_RT_PRIO;
+
+ if (is_task_rq(rt_rq)) {
+ se = __rt_edf_first(&rt_rq->active);
+ if (se) {
+ curp = rt_task_of(se)->prio;
+ next_se = __rt_edf_next(se);
+ if (next_se)
+ nextp = rt_task_of(next_se)->prio;
+ }
+ } else {
+ for (node = rb_first(&rt_rq->active.rb_root);
+ node; node = rb_next(node)) {
+ se = rb_entry(node, struct sched_rt_entity, rb_node);
+ child = group_rt_rq(se);
+
+ if (child->highest_prio.next < curp) {
+ curp = child->highest_prio.curr;
+ nextp = child->highest_prio.next;
+ } else if (child->highest_prio.curr < curp) {
+ nextp = curp;
+ curp = child->highest_prio.curr;
+ if (child->highest_prio.next < nextp)
+ nextp = child->highest_prio.next;
+ } else if (child->highest_prio.curr < nextp)
+ nextp = child->highest_prio.curr;
+ }
+ }

- if (next && rt_prio(next->prio))
- return next->prio;
- else
- return MAX_RT_PRIO;
+ *curr = curp;
+ *next = nextp;
+}
+
+static inline int next_prio(struct rt_rq *rt_rq)
+{
+ int curp, nextp;
+
+ find_highest_prios(rt_rq, &curp, &nextp);
+ return nextp;
}

static void
@@ -554,7 +595,6 @@ inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
struct rq *rq = rq_of_rt_rq(rt_rq);

if (prio < prev_prio) {
-
/*
* If the new task is higher in priority than anything on the
* run-queue, we know that the previous high becomes our
@@ -576,18 +616,22 @@ inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
/*
* Otherwise, we need to recompute next-highest
*/
- rt_rq->highest_prio.next = next_prio(rq);
+ rt_rq->highest_prio.next = next_prio(rt_rq);
}

static void
-dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
+dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prevp, int nextp)
{
struct rq *rq = rq_of_rt_rq(rt_rq);

- if (rt_rq->rt_nr_running && (prio <= rt_rq->highest_prio.next))
- rt_rq->highest_prio.next = next_prio(rq);
+ if (rt_rq->rt_nr_running && (prio <= rt_rq->highest_prio.next)) {
+ if (nextp == -1)
+ rt_rq->highest_prio.next = next_prio(rt_rq);
+ else
+ rt_rq->highest_prio.next = nextp;
+ }

- if (rq->online && rt_rq->highest_prio.curr != prev_prio)
+ if (rq->online && rt_rq->highest_prio.curr != prevp)
cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio.curr);
}

@@ -596,7 +640,8 @@ dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
static inline
void inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
static inline
-void dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
+void dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio,
+ int next_prio) {}

#endif /* CONFIG_SMP */

@@ -615,8 +660,7 @@ inc_rt_prio(struct rt_rq *rt_rq, int prio)
static void
dec_rt_prio(struct rt_rq *rt_rq, int prio)
{
- struct sched_rt_entity *rt_se;
- int prev_prio = rt_rq->highest_prio.curr;
+ int prev_prio = rt_rq->highest_prio.curr, curr_prio, next_prio = -1;

if (rt_rq->rt_nr_running) {

@@ -627,14 +671,14 @@ dec_rt_prio(struct rt_rq *rt_rq, int prio)
* we may have some recomputation to do
*/
if (prio == prev_prio) {
- rt_se = __rt_edf_first(&rt_rq->active);
- rt_rq->highest_prio.curr = rt_se_prio(rt_se);
+ find_highest_prios(rt_rq, &curr_prio, &next_prio);
+ rt_rq->highest_prio.curr = curr_prio;
}

} else
rt_rq->highest_prio.curr = MAX_RT_PRIO;

- dec_rt_prio_smp(rt_rq, prio, prev_prio);
+ dec_rt_prio_smp(rt_rq, prio, prev_prio, next_prio);
}

#else
--
1.6.2.2

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