Messages in this thread Patch in this message | | | Date | Wed, 5 Jul 2017 11:31:36 +0530 | From | Viresh Kumar <> | Subject | Re: [PATCH v2 3/6] cpufreq: schedutil: ensure max frequency while running RT/DL tasks |
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On 04-07-17, 18:34, Patrick Bellasi wrote: > diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c > index 004ae18..98704d8 100644 > --- a/kernel/sched/cpufreq_schedutil.c > +++ b/kernel/sched/cpufreq_schedutil.c > @@ -216,6 +216,7 @@ static void sugov_update_single(struct update_util_data *hook, u64 time, > struct cpufreq_policy *policy = sg_policy->policy; > unsigned long util, max; > unsigned int next_f; > + bool rt_mode; > bool busy; > > /* Skip updates generated by sugov kthreads */ > @@ -230,7 +231,15 @@ static void sugov_update_single(struct update_util_data *hook, u64 time, > > busy = sugov_cpu_is_busy(sg_cpu); > > - if (flags & SCHED_CPUFREQ_RT_DL) { > + /* > + * While RT/DL tasks are running we do not want FAIR tasks to > + * overvrite this CPU's flags, still we can update utilization and > + * frequency (if required/possible) to be fair with these tasks. > + */ > + rt_mode = task_has_dl_policy(current) || > + task_has_rt_policy(current) || > + (flags & SCHED_CPUFREQ_RT_DL);
We may want to create a separate inline function for above, as it is already used twice in this patch.
But I was wondering if we can get some help from the scheduler to avoid such code here. I understand that we don't want to do the aggregation in the scheduler to keep it clean and keep such governor specific thing here.
But what about clearing the sched-class's flag from .pick_next_task() callback when they return NULL ?
What about something like this instead (completely untested), with which we don't need the 2/3 patch as well:
diff --git a/include/linux/sched/cpufreq.h b/include/linux/sched/cpufreq.h index d2be2ccbb372..e81a6b5591f5 100644 --- a/include/linux/sched/cpufreq.h +++ b/include/linux/sched/cpufreq.h @@ -11,6 +11,10 @@ #define SCHED_CPUFREQ_DL (1U << 1) #define SCHED_CPUFREQ_IOWAIT (1U << 2) +#define SCHED_CPUFREQ_CLEAR (1U << 31) +#define SCHED_CPUFREQ_CLEAR_RT (SCHED_CPUFREQ_CLEAR | SCHED_CPUFREQ_RT) +#define SCHED_CPUFREQ_CLEAR_DL (SCHED_CPUFREQ_CLEAR | SCHED_CPUFREQ_DL) + #define SCHED_CPUFREQ_RT_DL (SCHED_CPUFREQ_RT | SCHED_CPUFREQ_DL) #ifdef CONFIG_CPU_FREQ diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c index 076a2e31951c..f32e15d59d62 100644 --- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c @@ -218,6 +218,9 @@ static void sugov_update_single(struct update_util_data *hook, u64 time, unsigned int next_f; bool busy; + if (flags & SCHED_CPUFREQ_CLEAR) + return; + sugov_set_iowait_boost(sg_cpu, time, flags); sg_cpu->last_update = time; @@ -296,7 +299,13 @@ static void sugov_update_shared(struct update_util_data *hook, u64 time, sg_cpu->util = util; sg_cpu->max = max; - sg_cpu->flags = flags; + + if (unlikely(flags & SCHED_CPUFREQ_CLEAR)) { + sg_cpu->flags &= ~(flags & ~SCHED_CPUFREQ_CLEAR); + return; + } + + sg_cpu->flags |= flags; sugov_set_iowait_boost(sg_cpu, time, flags); sg_cpu->last_update = time; diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index a2ce59015642..441d6153d654 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1203,8 +1203,10 @@ pick_next_task_dl(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) if (prev->sched_class == &dl_sched_class) update_curr_dl(rq); - if (unlikely(!dl_rq->dl_nr_running)) + if (unlikely(!dl_rq->dl_nr_running)) { + cpufreq_update_this_cpu(rq, SCHED_CPUFREQ_CLEAR_DL); return NULL; + } put_prev_task(rq, prev); diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 979b7341008a..bca9e4bb7ec4 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1556,8 +1556,10 @@ pick_next_task_rt(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) if (prev->sched_class == &rt_sched_class) update_curr_rt(rq); - if (!rt_rq->rt_queued) + if (!rt_rq->rt_queued) { + cpufreq_update_this_cpu(rq, SCHED_CPUFREQ_CLEAR_RT); return NULL; + } put_prev_task(rq, prev);
-- viresh
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