From 51eff27cb559af7f2b8fc4439893ad249576b5cd Mon Sep 17 00:00:00 2001 From: Juri Lelli Date: Wed, 19 Aug 2015 19:47:12 +0100 Subject: [PATCH] sched/fair: add triggers for OPP change requests 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. [smuckle@linaro.org: resolve merge conflicts, define task_new, use renamed static key sched_freq] cc: Ingo Molnar cc: Peter Zijlstra Signed-off-by: Juri Lelli Signed-off-by: Steve Muckle --- kernel/sched/fair.c | 46 ++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 45 insertions(+), 1 deletion(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 3eb5beb590a8..844788da00be 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4144,6 +4144,21 @@ static inline void hrtick_update(struct rq *rq) } #endif +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_freq()) + return; + + /* Convert scale-invariant capacity to cpu. */ + req_cap = cpu_util(cpu) * SCHED_CAPACITY_SCALE / capacity_orig_of(cpu); + set_cfs_cpu_capacity(cpu, true, req_cap); +} + static bool cpu_overutilized(int cpu); /* @@ -4193,6 +4208,20 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) if (!task_new && !rq->rd->overutilized && cpu_overutilized(rq->cpu)) rq->rd->overutilized = true; + + /* + * 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); } @@ -4251,9 +4280,24 @@ 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) { + if (rq->cfs.nr_running) + update_capacity_of(cpu_of(rq)); + else if (sched_freq()) + set_cfs_cpu_capacity(cpu_of(rq), false, 0); + } + } hrtick_update(rq); } -- 2.34.1