From: Juri Lelli <[email protected]> Each time a task is {en,de}queued we might need to adapt the current frequency to the new usage. Add triggers on {en,de}queue_task_fair() for this purpose. Only trigger a freq request if we are effectively waking up or going to sleep. Filter out load balancing related calls to reduce the number of triggers.
cc: Ingo Molnar <[email protected]> cc: Peter Zijlstra <[email protected]> Signed-off-by: Juri Lelli <[email protected]> --- kernel/sched/fair.c | 47 +++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 45 insertions(+), 2 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index b35d90b..ebf86b4 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4075,6 +4075,26 @@ static inline void hrtick_update(struct rq *rq) } #endif +/* + * ~20% capacity margin that we add to every capacity change + * request to provide some head room if task utilization further + * increases. + */ +static unsigned int capacity_margin = 1280; +static unsigned long capacity_orig_of(int cpu); +static int cpu_util(int cpu); + +static void update_capacity_of(int cpu) +{ + unsigned long req_cap; + + if (!sched_energy_freq()) + return; + + req_cap = cpu_util(cpu) * capacity_margin / capacity_orig_of(cpu); + cpufreq_sched_set_cap(cpu, req_cap); +} + struct static_key __sched_energy_freq __read_mostly = STATIC_KEY_INIT_FALSE; /* @@ -4087,6 +4107,7 @@ 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); for_each_sched_entity(se) { if (se->on_rq) @@ -4118,9 +4139,22 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) update_cfs_shares(cfs_rq); } - if (!se) + if (!se) { add_nr_running(rq, 1); + /* + * We want to potentially trigger a freq switch request only for + * tasks that are waking up; this is 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) + update_capacity_of(cpu_of(rq)); + } hrtick_update(rq); } @@ -4178,9 +4212,18 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) update_cfs_shares(cfs_rq); } - if (!se) + if (!se) { sub_nr_running(rq, 1); + /* + * We want to potentially trigger a freq switch request only for + * tasks that are going to sleep; this is 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. + */ + if (task_sleep) + update_capacity_of(cpu_of(rq)); + } hrtick_update(rq); } -- 2.5.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
