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-rw-r--r--kernel/sched_rt.c49
1 files changed, 36 insertions, 13 deletions
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 52d88f1..61d1988 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -296,29 +296,36 @@ static struct task_struct *pick_next_highest_task_rt(struct rq *rq,
}
static DEFINE_PER_CPU(cpumask_t, local_cpu_mask);
-static DEFINE_PER_CPU(cpumask_t, valid_cpu_mask);
static int find_lowest_cpus(struct task_struct *task, cpumask_t *lowest_mask)
{
- int cpu;
- cpumask_t *valid_mask = &__get_cpu_var(valid_cpu_mask);
int lowest_prio = -1;
+ int lowest_cpu = -1;
int count = 0;
+ int cpu;
- cpus_clear(*lowest_mask);
- cpus_and(*valid_mask, cpu_online_map, task->cpus_allowed);
+ cpus_and(*lowest_mask, cpu_online_map, task->cpus_allowed);
/*
* Scan each rq for the lowest prio.
*/
- for_each_cpu_mask(cpu, *valid_mask) {
+ for_each_cpu_mask(cpu, *lowest_mask) {
struct rq *rq = cpu_rq(cpu);
/* We look for lowest RT prio or non-rt CPU */
if (rq->rt.highest_prio >= MAX_RT_PRIO) {
- if (count)
+ /*
+ * if we already found a low RT queue
+ * and now we found this non-rt queue
+ * clear the mask and set our bit.
+ * Otherwise just return the queue as is
+ * and the count==1 will cause the algorithm
+ * to use the first bit found.
+ */
+ if (lowest_cpu != -1) {
cpus_clear(*lowest_mask);
- cpu_set(rq->cpu, *lowest_mask);
+ cpu_set(rq->cpu, *lowest_mask);
+ }
return 1;
}
@@ -328,13 +335,29 @@ static int find_lowest_cpus(struct task_struct *task, cpumask_t *lowest_mask)
if (rq->rt.highest_prio > lowest_prio) {
/* new low - clear old data */
lowest_prio = rq->rt.highest_prio;
- if (count) {
- cpus_clear(*lowest_mask);
- count = 0;
- }
+ lowest_cpu = cpu;
+ count = 0;
}
- cpu_set(rq->cpu, *lowest_mask);
count++;
+ } else
+ cpu_clear(cpu, *lowest_mask);
+ }
+
+ /*
+ * Clear out all the set bits that represent
+ * runqueues that were of higher prio than
+ * the lowest_prio.
+ */
+ if (lowest_cpu > 0) {
+ /*
+ * Perhaps we could add another cpumask op to
+ * zero out bits. Like cpu_zero_bits(cpumask, nrbits);
+ * Then that could be optimized to use memset and such.
+ */
+ for_each_cpu_mask(cpu, *lowest_mask) {
+ if (cpu >= lowest_cpu)
+ break;
+ cpu_clear(cpu, *lowest_mask);
}
}
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