Messages in this thread | | | Date | Tue, 18 Feb 2020 17:27:46 +0000 | From | Qais Yousef <> | Subject | Re: [PATCH 1/3] sched/rt: cpupri_find: implement fallback mechanism for !fit case |
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On 02/18/20 11:46, Steven Rostedt wrote: > On Mon, 17 Feb 2020 23:45:49 +0000 > Qais Yousef <qais.yousef@arm.com> wrote: > > > --- a/kernel/sched/rt.c > > +++ b/kernel/sched/rt.c > > @@ -14,6 +14,8 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun); > > > > struct rt_bandwidth def_rt_bandwidth; > > > > +typedef bool (*fitness_fn_t)(struct task_struct *p, int cpu); > > + > > static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer) > > { > > struct rt_bandwidth *rt_b = > > @@ -1708,6 +1710,7 @@ static int find_lowest_rq(struct task_struct *task) > > struct cpumask *lowest_mask = this_cpu_cpumask_var_ptr(local_cpu_mask); > > int this_cpu = smp_processor_id(); > > int cpu = task_cpu(task); > > + fitness_fn_t fitness_fn; > > > > /* Make sure the mask is initialized first */ > > if (unlikely(!lowest_mask)) > > @@ -1716,8 +1719,17 @@ static int find_lowest_rq(struct task_struct *task) > > if (task->nr_cpus_allowed == 1) > > return -1; /* No other targets possible */ > > > > + /* > > + * Help cpupri_find avoid the cost of looking for a fitting CPU when > > + * not really needed. > > + */ > > + if (static_branch_unlikely(&sched_asym_cpucapacity)) > > + fitness_fn = rt_task_fits_capacity; > > + else > > + fitness_fn = NULL; > > + > > if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask, > > - rt_task_fits_capacity)) > > + fitness_fn)) > > return -1; /* No targets found */ > > > > /* > > > If we are going to use static branches, then lets just remove the > parameter totally. That is, make two functions (with helpers), where > one needs this fitness function the other does not. > > if (static_branch_unlikely(&sched_asym_cpu_capacity)) > ret = cpupri_find_fitness(...); > else > ret = cpupri_find(...); > > if (!ret) > return -1; > > Something like that?
Is there any implication on code generation here?
I like my flavour better tbh. But I don't mind refactoring the function out if it does make it more readable.
Thanks
-- Qais Yousef
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