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SubjectRe: [RFC 5/6] sched: pack the idle load balance
On Monday 29 October 2012 06:57 PM, Vincent Guittot wrote:
> On 24 October 2012 17:21, Santosh Shilimkar <santosh.shilimkar@ti.com> wrote:
>> On Sunday 07 October 2012 01:13 PM, Vincent Guittot wrote:
>>>
>>> Look for an idle CPU close the pack buddy CPU whenever possible.
>>
>> s/close/close to
>
> yes
>
>>
>>> The goal is to prevent the wake up of a CPU which doesn't share the power
>>> line of the pack CPU
>>>
>>> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
>>> ---
>>> kernel/sched/fair.c | 18 ++++++++++++++++++
>>> 1 file changed, 18 insertions(+)
>>>
>>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
>>> index 6df53b5..f76acdc 100644
>>> --- a/kernel/sched/fair.c
>>> +++ b/kernel/sched/fair.c
>>> @@ -5158,7 +5158,25 @@ static struct {
>>>
>>> static inline int find_new_ilb(int call_cpu)
>>> {
>>> + struct sched_domain *sd;
>>> int ilb = cpumask_first(nohz.idle_cpus_mask);
>>> + int buddy = per_cpu(sd_pack_buddy, call_cpu);
>>> +
>>> + /*
>>> + * If we have a pack buddy CPU, we try to run load balance on a
>>> CPU
>>> + * that is close to the buddy.
>>> + */
>>> + if (buddy != -1)
>>> + for_each_domain(buddy, sd) {
>>> + if (sd->flags & SD_SHARE_CPUPOWER)
>>> + continue;
>>
>> Do you mean SD_SHARE_POWERLINE here ?
>
> No, I just don't want to take hyperthread level for ILB
>
>>
>>> +
>>> + ilb = cpumask_first_and(sched_domain_span(sd),
>>> + nohz.idle_cpus_mask);
>>> +
>>> + if (ilb < nr_cpu_ids)
>>> + break;
>>> + }
>>>
>>> if (ilb < nr_cpu_ids && idle_cpu(ilb))
>>> return ilb;
>>>
>> Can you please expand "idle CPU _close_ the pack buddy CPU" ?
>
> The goal is to packed the tasks on the pack buddy CPU so when the
> scheduler needs to start ILB, I try to wake up a CPU that is close to
> the buddy and preferably in the same cluster
>
I see your point now. Thanks for clarification.

Regards
santosh



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