On Fri, 2014-01-17 at 10:14 +0800, Alex Shi wrote:
> On 01/16/2014 09:52 PM, Mike Galbraith wrote:
> > On Thu, 2014-01-16 at 21:13 +0800, Alex Shi wrote:
> >> Add Mike Galbraith.
> >>
> >> Any one like to give some comments?
> >>
> >> On 01/15/2014 10:23 PM, Alex Shi wrote:
> >>> If the sd domain just has one group, then we must be caught the
> >>> i == target later, and then goes to deeper level domain.
> >>> So just skip this domain checking to save some instructions.
> >>>
> >>> Signed-off-by: Alex Shi <alex....@linaro.org>
> >>> ---
> >>> kernel/sched/fair.c | 5 +++++
> >>> 1 file changed, 5 insertions(+)
> >>>
> >>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> >>> index c7395d9..3265fbc 100644
> >>> --- a/kernel/sched/fair.c
> >>> +++ b/kernel/sched/fair.c
> >>> @@ -4196,6 +4196,11 @@ static int select_idle_sibling(struct task_struct
> >>> *p, int target)
> >>> sd = rcu_dereference(per_cpu(sd_llc, target));
> >>> for_each_lower_domain(sd) {
> >>> sg = sd->groups;
> >>> +
> >>> + /* skip single group domain */
> >>> + if (sg == sg->next)
> >>> + continue;
> >
> > When is that gonna happen?
>
> I had seen this in a Intel platform, you may have both CPU domain and MC
> domain layer, because the domain flag is different, then they can not be
> merged. and then the CPU domain just has one group.
But sd starts at MC.
-Mike
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