cpumask: simplify sched_rt.c Impact: cleanup, remove on-stack cpumask_t find_lowest_rq() wants to call pick_optimal_cpu() on the intersection of sched_domain_span(sd) and lowest_mask. Rather than doing a cpus_and into a temporary, we can open-code it. This actually makes the code slightly clearer, IMHO. Signed-off-by: Rusty Russell To: Steven Rostedt Cc: Ingo Molnar --- kernel/sched_rt.c | 43 +++++++++++++++++++------------------------ 1 file changed, 19 insertions(+), 24 deletions(-) diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c --- a/kernel/sched_rt.c +++ b/kernel/sched_rt.c @@ -953,21 +953,6 @@ static struct task_struct *pick_next_hig static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask); -static inline int pick_optimal_cpu(int this_cpu, const struct cpumask *mask) -{ - int first; - - /* "this_cpu" is cheaper to preempt than a remote processor */ - if ((this_cpu != -1) && cpumask_test_cpu(this_cpu, mask)) - return this_cpu; - - first = cpumask_first(mask); - if (first < nr_cpu_ids) - return first; - - return -1; -} - static int find_lowest_rq(struct task_struct *task) { struct sched_domain *sd; @@ -1003,20 +988,24 @@ static int find_lowest_rq(struct task_st * Otherwise, we consult the sched_domains span maps to figure * out which cpu is logically closest to our hot cache data. */ - if (this_cpu == cpu) - this_cpu = -1; /* Skip this_cpu opt if the same */ + if (!cpumask_test_cpu(this_cpu, lowest_mask)) + this_cpu = -1; /* Skip this_cpu opt if not among lowest */ for_each_domain(cpu, sd) { if (sd->flags & SD_WAKE_AFFINE) { - cpumask_t domain_mask; int best_cpu; - cpumask_and(&domain_mask, sched_domain_span(sd), - lowest_mask); + /* + * "this_cpu" is cheaper to preempt than a + * remote processor. + */ + if (this_cpu != -1 && + cpumask_test_cpu(this_cpu, sched_domain_span(sd))) + return this_cpu; - best_cpu = pick_optimal_cpu(this_cpu, - &domain_mask); - if (best_cpu != -1) + best_cpu = cpumask_first_and(lowest_mask, + sched_domain_span(sd)); + if (best_cpu < nr_cpu_ids) return best_cpu; } } @@ -1026,7 +1015,13 @@ static int find_lowest_rq(struct task_st * just give the caller *something* to work with from the compatible * locations. */ - return pick_optimal_cpu(this_cpu, lowest_mask); + if (this_cpu != -1) + return this_cpu; + + cpu = cpumask_any(lowest_mask); + if (cpu < nr_cpu_ids) + return cpu; + return -1; } /* Will lock the rq it finds */