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sched/{core,fair}: trigger OPP change request on fork()

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Patch "sched/fair: add triggers for OPP change requests" introduced OPP
change triggers for enqueue_task_fair(), but the trigger was operating only
for wakeups. Fact is that it makes sense to consider wakeup_new also (i.e.,
fork()), as we don't know anything about a newly created task and thus we
most certainly want to jump to max OPP to not harm performance too much.

However, it is not currently possible (or at least it wasn't evident to me
how to do so :/) to tell new wakeups from other (non wakeup) operations.

This patch introduces an additional flag in sched.h that is only set at
fork() time and it is then consumed in enqueue_task_fair() for our purpose.

cc: Ingo Molnar <mingo@redhat.com>
cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Steve Muckle <smuckle@linaro.org>
This commit is contained in:
Juri Lelli
2015-06-26 12:14:23 +01:00
committed by Leo Yan
parent ea429ccef1
commit 7ff814dd71
3 changed files with 5 additions and 7 deletions
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2
kernel/sched/core.c
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@@ -2387,7 +2387,7 @@ void wake_up_new_task(struct task_struct *p)
#endif
rq = __task_rq_lock(p);
activate_task(rq, p, 0);
activate_task(rq, p, ENQUEUE_WAKEUP_NEW);
p->on_rq = TASK_ON_RQ_QUEUED;
trace_sched_wakeup_new(p);
check_preempt_curr(rq, p, WF_FORK);

9
kernel/sched/fair.c
View File

@@ -4171,7 +4171,8 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
{
struct cfs_rq *cfs_rq;
struct sched_entity *se = &p->se;
int task_new = !(flags & ENQUEUE_WAKEUP);
int task_new = flags & ENQUEUE_WAKEUP_NEW;
int task_wakeup = flags & ENQUEUE_WAKEUP;
for_each_sched_entity(se) {
if (se->on_rq)
@@ -4215,12 +4216,8 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
* because we get here also during load balancing, but
* in these cases it seems wise to trigger as single
* request after load balancing is done.
*
* XXX: how about fork()? Do we need a special
* flag/something to tell if we are here after a
* fork() (wakeup_task_new)?
*/
if (!task_new)
if (task_new || task_wakeup)
update_capacity_of(cpu_of(rq));
}
hrtick_update(rq);

1
kernel/sched/sched.h
View File

@@ -1181,6 +1181,7 @@ static const u32 prio_to_wmult[40] = {
#endif
#define ENQUEUE_REPLENISH 0x08
#define ENQUEUE_RESTORE 0x10
#define ENQUEUE_WAKEUP_NEW 0x20
#define DEQUEUE_SLEEP 0x01
#define DEQUEUE_SAVE 0x02