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authorGregory Haskins <ghaskins@novell.com>2008-06-27 14:30:00 -0600
committerIngo Molnar <mingo@elte.hu>2008-07-04 12:50:22 +0200
commit2087a1ad822cd3a68b73338457047fcc54da726b (patch)
tree1ebc45b2499034ffe37b29bf7a748b8e992cd870 /kernel/sched.c
parentc4acb2c0669c5c5c9b28e9d02a34b5c67edf7092 (diff)
downloadlwn-2087a1ad822cd3a68b73338457047fcc54da726b.tar.gz
lwn-2087a1ad822cd3a68b73338457047fcc54da726b.zip
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>
Diffstat (limited to 'kernel/sched.c')
-rw-r--r--kernel/sched.c14
1 files changed, 14 insertions, 0 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index d99aeabeb72f..bbc40c3a0657 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1693,6 +1693,12 @@ static void set_load_weight(struct task_struct *p)
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 enqueue_task(struct rq *rq, struct task_struct *p, int wakeup)
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 @@ out_running:
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;