sched: add avg-overlap support to RT tasks
We have the notion of tracking process-coupling (a.k.a. buddy-wake) via
the p->se.last_wake / p->se.avg_overlap facilities, but it is only used
for cfs to cfs interactions. There is no reason why an rt to cfs
interaction cannot share in establishing a relationhip in a similar
manner.
Because PREEMPT_RT runs many kernel threads as FIFO priority, we often
times have heavy interaction between RT threads waking CFS applications.
This patch offers a substantial boost (50-60%+) in perfomance under those
circumstances.
Signed-off-by: Gregory Haskins <ghaskins@novell.com>
Cc: npiggin@suse.de
Cc: rostedt@goodmis.org
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/sched.c b/kernel/sched.c
index d99aeab..bbc40c3 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1693,6 +1693,12 @@
p->se.load.inv_weight = prio_to_wmult[p->static_prio - MAX_RT_PRIO];
}
+static void update_avg(u64 *avg, u64 sample)
+{
+ s64 diff = sample - *avg;
+ *avg += diff >> 3;
+}
+
static void enqueue_task(struct rq *rq, struct task_struct *p, int wakeup)
{
sched_info_queued(p);
@@ -1702,6 +1708,12 @@
static void dequeue_task(struct rq *rq, struct task_struct *p, int sleep)
{
+ if (sleep && p->se.last_wakeup) {
+ update_avg(&p->se.avg_overlap,
+ p->se.sum_exec_runtime - p->se.last_wakeup);
+ p->se.last_wakeup = 0;
+ }
+
p->sched_class->dequeue_task(rq, p, sleep);
p->se.on_rq = 0;
}
@@ -2313,6 +2325,8 @@
p->sched_class->task_wake_up(rq, p);
#endif
out:
+ current->se.last_wakeup = current->se.sum_exec_runtime;
+
task_rq_unlock(rq, &flags);
return success;