Con Kolivas wrote:
This patch improves throughput with the smp nice balancing code. Many thanks
to Martin Bligh for the usage of his regression testing bed to confirm the
effectiveness of various patches.
Con,
This doesn't build on non SMP systems due to the migration_thread field
only being defined for SMP. Attached is a copy of a slightly modified
PlugSched version of the patch which I used to fix the problem in
PlugSched. Even though it's for a different file it should be easy to
copy over.
Peter
--
Peter Williams [email protected]
"Learning, n. The kind of ignorance distinguishing the studious."
-- Ambrose Bierce
Index: MM-2.6.12/include/linux/sched_pvt.h
===================================================================
--- MM-2.6.12.orig/include/linux/sched_pvt.h 2005-06-28 10:11:47.000000000 +1000
+++ MM-2.6.12/include/linux/sched_pvt.h 2005-06-28 10:37:14.000000000 +1000
@@ -393,6 +393,11 @@
{
rq->prio_bias -= MAX_STATIC_PRIO - prio;
}
+
+static inline int is_migration_thread(const task_t *p, const runqueue_t *rq)
+{
+ return p == rq->migration_thread;
+}
#else
static inline void inc_prio_bias(runqueue_t *rq, int prio)
{
@@ -401,23 +406,35 @@
static inline void dec_prio_bias(runqueue_t *rq, int prio)
{
}
+
+static inline int is_migration_thread(const task_t *p, const runqueue_t *rq)
+{
+ return 0;
+}
#endif
static inline void inc_nr_running(task_t *p, runqueue_t *rq)
{
rq->nr_running++;
- if (rt_task(p))
- inc_prio_bias(rq, p->prio);
- else
+ if (rt_task(p)) {
+ if (!is_migration_thread(p, rq))
+ /*
+ * The migration thread does the actual balancing. Do
+ * not bias by its priority as the ultra high priority
+ * will skew balancing adversely.
+ */
+ inc_prio_bias(rq, p->prio);
+ } else
inc_prio_bias(rq, p->static_prio);
}
static inline void dec_nr_running(task_t *p, runqueue_t *rq)
{
rq->nr_running--;
- if (rt_task(p))
- dec_prio_bias(rq, p->prio);
- else
+ if (rt_task(p)) {
+ if (!is_migration_thread(p, rq))
+ dec_prio_bias(rq, p->prio);
+ } else
dec_prio_bias(rq, p->static_prio);
}
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