Messages in this thread Patch in this message | | | Date | Tue, 18 Feb 2020 11:46:58 -0500 | From | Steven Rostedt <> | Subject | Re: [PATCH 1/3] sched/rt: cpupri_find: implement fallback mechanism for !fit case |
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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?
-- Steve
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