sched/fair: Rearrange select_task_rq_fair() to optimize it
Rearrange select_task_rq_fair() a bit to avoid executing some conditional statements in few specific code-paths. That gets rid of the goto as well. This shouldn't result in any functional changes. Tested-by: Rohit Jain <rohit.k.jain@oracle.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vincent Guittot <vincent.guittot@linaro.org> Link: http://lkml.kernel.org/r/20831b8d237bf3a20e4e328286f678b425ff04c9.1524738578.git.viresh.kumar@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -6613,7 +6613,7 @@ static int wake_cap(struct task_struct *p, int cpu, int prev_cpu)
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static int
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static int
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select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_flags)
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select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_flags)
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{
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{
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struct sched_domain *tmp, *affine_sd = NULL, *sd = NULL;
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struct sched_domain *tmp, *sd = NULL;
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int cpu = smp_processor_id();
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int cpu = smp_processor_id();
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int new_cpu = prev_cpu;
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int new_cpu = prev_cpu;
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int want_affine = 0;
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int want_affine = 0;
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@ -6636,7 +6636,10 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f
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*/
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*/
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if (want_affine && (tmp->flags & SD_WAKE_AFFINE) &&
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if (want_affine && (tmp->flags & SD_WAKE_AFFINE) &&
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cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) {
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cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) {
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affine_sd = tmp;
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if (cpu != prev_cpu)
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new_cpu = wake_affine(tmp, p, cpu, prev_cpu, sync);
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sd = NULL; /* Prefer wake_affine over balance flags */
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break;
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break;
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}
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}
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@ -6646,33 +6649,25 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f
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break;
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break;
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}
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}
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if (affine_sd) {
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if (unlikely(sd)) {
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sd = NULL; /* Prefer wake_affine over balance flags */
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/* Slow path */
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if (cpu == prev_cpu)
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goto pick_cpu;
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new_cpu = wake_affine(affine_sd, p, cpu, prev_cpu, sync);
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}
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if (sd && !(sd_flag & SD_BALANCE_FORK)) {
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/*
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/*
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* We're going to need the task's util for capacity_spare_wake
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* We're going to need the task's util for capacity_spare_wake
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* in find_idlest_group. Sync it up to prev_cpu's
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* in find_idlest_group. Sync it up to prev_cpu's
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* last_update_time.
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* last_update_time.
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*/
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*/
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sync_entity_load_avg(&p->se);
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if (!(sd_flag & SD_BALANCE_FORK))
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}
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sync_entity_load_avg(&p->se);
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if (!sd) {
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pick_cpu:
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if (sd_flag & SD_BALANCE_WAKE) { /* XXX always ? */
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new_cpu = select_idle_sibling(p, prev_cpu, new_cpu);
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if (want_affine)
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current->recent_used_cpu = cpu;
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}
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} else {
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new_cpu = find_idlest_cpu(sd, p, cpu, prev_cpu, sd_flag);
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new_cpu = find_idlest_cpu(sd, p, cpu, prev_cpu, sd_flag);
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} else if (sd_flag & SD_BALANCE_WAKE) { /* XXX always ? */
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/* Fast path */
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new_cpu = select_idle_sibling(p, prev_cpu, new_cpu);
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if (want_affine)
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current->recent_used_cpu = cpu;
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}
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}
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rcu_read_unlock();
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rcu_read_unlock();
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