Commit-ID: f1d88b4468188ddcd2620b8d612068faf6662a62 Gitweb: https://git.kernel.org/tip/f1d88b4468188ddcd2620b8d612068faf6662a62 Author: Viresh Kumar <viresh.ku...@linaro.org> AuthorDate: Thu, 26 Apr 2018 16:00:50 +0530 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Fri, 4 May 2018 10:00:07 +0200
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.j...@oracle.com> Signed-off-by: Viresh Kumar <viresh.ku...@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Reviewed-by: Valentin Schneider <valentin.schnei...@arm.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: Vincent Guittot <vincent.guit...@linaro.org> Link: http://lkml.kernel.org/r/20831b8d237bf3a20e4e328286f678b425ff04c9.1524738578.git.viresh.ku...@linaro.org Signed-off-by: Ingo Molnar <mi...@kernel.org> --- kernel/sched/fair.c | 37 ++++++++++++++++--------------------- 1 file changed, 16 insertions(+), 21 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index e3002e5ada31..4b346f358005 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6613,7 +6613,7 @@ static int wake_cap(struct task_struct *p, int cpu, int prev_cpu) static int select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_flags) { - struct sched_domain *tmp, *affine_sd = NULL, *sd = NULL; + struct sched_domain *tmp, *sd = NULL; int cpu = smp_processor_id(); int new_cpu = prev_cpu; int want_affine = 0; @@ -6636,7 +6636,10 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f */ if (want_affine && (tmp->flags & SD_WAKE_AFFINE) && cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) { - affine_sd = tmp; + if (cpu != prev_cpu) + new_cpu = wake_affine(tmp, p, cpu, prev_cpu, sync); + + sd = NULL; /* Prefer wake_affine over balance flags */ break; } @@ -6646,33 +6649,25 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f break; } - if (affine_sd) { - sd = NULL; /* Prefer wake_affine over balance flags */ - if (cpu == prev_cpu) - goto pick_cpu; - - new_cpu = wake_affine(affine_sd, p, cpu, prev_cpu, sync); - } + if (unlikely(sd)) { + /* Slow path */ - if (sd && !(sd_flag & SD_BALANCE_FORK)) { /* * We're going to need the task's util for capacity_spare_wake * in find_idlest_group. Sync it up to prev_cpu's * last_update_time. */ - sync_entity_load_avg(&p->se); - } - - if (!sd) { -pick_cpu: - if (sd_flag & SD_BALANCE_WAKE) { /* XXX always ? */ - new_cpu = select_idle_sibling(p, prev_cpu, new_cpu); + if (!(sd_flag & SD_BALANCE_FORK)) + sync_entity_load_avg(&p->se); - if (want_affine) - current->recent_used_cpu = cpu; - } - } else { new_cpu = find_idlest_cpu(sd, p, cpu, prev_cpu, sd_flag); + } else if (sd_flag & SD_BALANCE_WAKE) { /* XXX always ? */ + /* Fast path */ + + new_cpu = select_idle_sibling(p, prev_cpu, new_cpu); + + if (want_affine) + current->recent_used_cpu = cpu; } rcu_read_unlock();
