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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>
This commit is contained in:
Gregory Haskins 2008-06-27 14:30:00 -06:00 committed by Ingo Molnar
parent c4acb2c066
commit 2087a1ad82
2 changed files with 16 additions and 19 deletions
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14
kernel/sched.c
View File

@ -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;

21
kernel/sched_fair.c
View File

@ -726,21 +726,6 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
__enqueue_entity(cfs_rq, se);
}
static void update_avg(u64 *avg, u64 sample)
{
s64 diff = sample - *avg;
*avg += diff >> 3;
}
static void update_avg_stats(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
if (!se->last_wakeup)
return;
update_avg(&se->avg_overlap, se->sum_exec_runtime - se->last_wakeup);
se->last_wakeup = 0;
}
static void
dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
{
@ -751,7 +736,6 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int sleep)
update_stats_dequeue(cfs_rq, se);
if (sleep) {
update_avg_stats(cfs_rq, se);
#ifdef CONFIG_SCHEDSTATS
if (entity_is_task(se)) {
struct task_struct *tsk = task_of(se);
@ -1196,9 +1180,9 @@ wake_affine(struct rq *rq, struct sched_domain *this_sd, struct rq *this_rq,
* a reasonable amount of time then attract this newly
* woken task:
*/
if (sync && balanced && curr->sched_class == &fair_sched_class) {
if (sync && balanced) {
if (curr->se.avg_overlap < sysctl_sched_migration_cost &&
p->se.avg_overlap < sysctl_sched_migration_cost)
p->se.avg_overlap < sysctl_sched_migration_cost)
return 1;
}
@ -1359,7 +1343,6 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)
return;
}
se->last_wakeup = se->sum_exec_runtime;
if (unlikely(se == pse))
return;