| Message ID | 1436293469-25707-36-git-send-email-morten.rasmussen@arm.com (mailing list archive) |
|---|---|
| State | RFC |
| Headers | show |
On Tue, Jul 07, 2015 at 07:24:18PM +0100, Morten Rasmussen wrote: > With energy-aware scheduling enabled nohz_kick_needed() generates many > nohz idle-balance kicks which lead to nothing when multiple tasks get > packed on a single cpu to save energy. This causes unnecessary wake-ups > and hence wastes energy. Make these conditions depend on !energy_aware() > for now until the energy-aware nohz story gets sorted out. The patch does slightly more; it also allows the kick if over utilized. But disabling this will allow getting 'stuck' in certain over loaded situations because we're not kicking the balancer. I think you need more justification for doing this. -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 97eb83e..8e0cbd4 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -8424,12 +8424,13 @@ static inline bool nohz_kick_needed(struct rq *rq) if (time_before(now, nohz.next_balance)) return false; - if (rq->nr_running >= 2) + if (rq->nr_running >= 2 && + (!energy_aware() || cpu_overutilized(cpu))) return true; rcu_read_lock(); sd = rcu_dereference(per_cpu(sd_busy, cpu)); - if (sd) { + if (sd && !energy_aware()) { sgc = sd->groups->sgc; nr_busy = atomic_read(&sgc->nr_busy_cpus);
With energy-aware scheduling enabled nohz_kick_needed() generates many nohz idle-balance kicks which lead to nothing when multiple tasks get packed on a single cpu to save energy. This causes unnecessary wake-ups and hence wastes energy. Make these conditions depend on !energy_aware() for now until the energy-aware nohz story gets sorted out. cc: Ingo Molnar <mingo@redhat.com> cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com> --- kernel/sched/fair.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)