| Message ID | 1466615004-3503-4-git-send-email-morten.rasmussen@arm.com |
|---|---|
| State | Superseded |
| Headers | show |
On 22 June 2016 at 19:03, Morten Rasmussen <morten.rasmussen@arm.com> wrote: > In the current find_idlest_group()/find_idlest_cpu() search we end up > calling find_idlest_cpu() in a sched_group containing only one cpu in > the end. Checking idle-states becomes pointless when there is no > alternative, so bail out instead. > > cc: Ingo Molnar <mingo@redhat.com> > cc: Peter Zijlstra <peterz@infradead.org> > > Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com> > --- > kernel/sched/fair.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index eec8e29104f9..216db302e87d 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -5123,6 +5123,10 @@ find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu) > int shallowest_idle_cpu = -1; > int i; > > + /* Check if we have any choice */ > + if (group->group_weight == 1) > + return cpumask_first(sched_group_cpus(group)); > + > /* Traverse only the allowed CPUs */ > for_each_cpu_and(i, sched_group_cpus(group), tsk_cpus_allowed(p)) { > if (idle_cpu(i)) { FWIW, you can add my Acked-by: : Vincent Guittot <vincent.guittot@linaro.org> > -- > 1.9.1 >
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index eec8e29104f9..216db302e87d 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5123,6 +5123,10 @@ find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu) int shallowest_idle_cpu = -1; int i; + /* Check if we have any choice */ + if (group->group_weight == 1) + return cpumask_first(sched_group_cpus(group)); + /* Traverse only the allowed CPUs */ for_each_cpu_and(i, sched_group_cpus(group), tsk_cpus_allowed(p)) { if (idle_cpu(i)) {
In the current find_idlest_group()/find_idlest_cpu() search we end up calling find_idlest_cpu() in a sched_group containing only one cpu in the end. Checking idle-states becomes pointless when there is no alternative, so bail out instead. cc: Ingo Molnar <mingo@redhat.com> cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com> --- kernel/sched/fair.c | 4 ++++ 1 file changed, 4 insertions(+) -- 1.9.1