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Subject[PATCH v4 11/20] RT: Break out the search function
From: Gregory Haskins <ghaskins@novell.com>

Isolate the search logic into a function so that it can be used later
in places other than find_locked_lowest_rq().

Signed-off-by: Gregory Haskins <ghaskins@novell.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
---
kernel/sched_rt.c | 66 +++++++++++++++++++++++++++++++-----------------------
1 file changed, 39 insertions(+), 27 deletions(-)
Index: linux-compile.git/kernel/sched_rt.c
===================================================================
--- linux-compile.git.orig/kernel/sched_rt.c 2007-11-20 19:53:04.000000000 -0500
+++ linux-compile.git/kernel/sched_rt.c 2007-11-20 19:53:05.000000000 -0500
@@ -260,54 +260,66 @@ static struct task_struct *pick_next_hig

static DEFINE_PER_CPU(cpumask_t, local_cpu_mask);

-/* Will lock the rq it finds */
-static struct rq *find_lock_lowest_rq(struct task_struct *task,
- struct rq *this_rq)
+static int find_lowest_rq(struct task_struct *task)
{
- struct rq *lowest_rq = NULL;
int cpu;
- int tries;
cpumask_t *cpu_mask = &__get_cpu_var(local_cpu_mask);
+ struct rq *lowest_rq = NULL;

cpus_and(*cpu_mask, cpu_online_map, task->cpus_allowed);

- for (tries = 0; tries < RT_MAX_TRIES; tries++) {
- /*
- * Scan each rq for the lowest prio.
- */
- for_each_cpu_mask(cpu, *cpu_mask) {
- struct rq *rq = &per_cpu(runqueues, cpu);
+ /*
+ * Scan each rq for the lowest prio.
+ */
+ for_each_cpu_mask(cpu, *cpu_mask) {
+ struct rq *rq = cpu_rq(cpu);

- if (cpu == this_rq->cpu)
- continue;
+ if (cpu == rq->cpu)
+ continue;

- /* We look for lowest RT prio or non-rt CPU */
- if (rq->rt.highest_prio >= MAX_RT_PRIO) {
- lowest_rq = rq;
- break;
- }
+ /* We look for lowest RT prio or non-rt CPU */
+ if (rq->rt.highest_prio >= MAX_RT_PRIO) {
+ lowest_rq = rq;
+ break;
+ }

- /* no locking for now */
- if (rq->rt.highest_prio > task->prio &&
- (!lowest_rq || rq->rt.highest_prio > lowest_rq->rt.highest_prio)) {
- lowest_rq = rq;
- }
+ /* no locking for now */
+ if (rq->rt.highest_prio > task->prio &&
+ (!lowest_rq || rq->rt.highest_prio > lowest_rq->rt.highest_prio)) {
+ lowest_rq = rq;
}
+ }
+
+ return lowest_rq ? lowest_rq->cpu : -1;
+}
+
+/* Will lock the rq it finds */
+static struct rq *find_lock_lowest_rq(struct task_struct *task,
+ struct rq *rq)
+{
+ struct rq *lowest_rq = NULL;
+ int cpu;
+ int tries;

- if (!lowest_rq)
+ for (tries = 0; tries < RT_MAX_TRIES; tries++) {
+ cpu = find_lowest_rq(task);
+
+ if (cpu == -1)
break;

+ lowest_rq = cpu_rq(cpu);
+
/* if the prio of this runqueue changed, try again */
- if (double_lock_balance(this_rq, lowest_rq)) {
+ if (double_lock_balance(rq, lowest_rq)) {
/*
* We had to unlock the run queue. In
* the mean time, task could have
* migrated already or had its affinity changed.
* Also make sure that it wasn't scheduled on its rq.
*/
- if (unlikely(task_rq(task) != this_rq ||
+ if (unlikely(task_rq(task) != rq ||
!cpu_isset(lowest_rq->cpu, task->cpus_allowed) ||
- task_running(this_rq, task) ||
+ task_running(rq, task) ||
!task->se.on_rq)) {
spin_unlock(&lowest_rq->lock);
lowest_rq = NULL;
--
-
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