sched/fair: Optimize find_busiest_queue()

Use for_each_cpu_and() and thereby avoid computing the capacity for
CPUs we know we're not interested in.

Reviewed-by: Paul Turner <pjt@google.com>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-lppceyv6kb3a19g8spmrn20b@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index ccf20e76b6b2e9ef913902bbf14ea481cae4c602..bedd30b168a57f43bf6db5af46fb56e730f5b403 100644 (file)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4946,7 +4946,7 @@ static struct rq *find_busiest_queue(struct lb_env *env,
        unsigned long busiest_load = 0, busiest_power = 1;
        int i;
 
-       for_each_cpu(i, sched_group_cpus(group)) {
+       for_each_cpu_and(i, sched_group_cpus(group), env->cpus) {
                unsigned long power = power_of(i);
                unsigned long capacity = DIV_ROUND_CLOSEST(power,
                                                           SCHED_POWER_SCALE);
@@ -4955,9 +4955,6 @@ static struct rq *find_busiest_queue(struct lb_env *env,
                if (!capacity)
                        capacity = fix_small_capacity(env->sd, group);
 
-               if (!cpumask_test_cpu(i, env->cpus))
-                       continue;
-
                rq = cpu_rq(i);
                wl = weighted_cpuload(i);