On 07/03/2013 04:50 PM, Peter Zijlstra wrote:
> On Wed, Jul 03, 2013 at 02:10:32PM +0800, Michael Wang wrote:
>> +static int wake_wide(struct task_struct *p)
>> +{
>> + int factor = nr_cpus_node(cpu_to_node(smp_processor_id()));
>
> That's still a cpumask_weight() in there...
Exactly, although the scale is lower but still it's a mask...
> we should avoid that. How about something like the below:
Amazing, cost will be lowest when we got such counter, will make them a
patch set and test again ;-)
Regards,
Michael Wang
>
>> +
>> + /*
>> + * Yeah, it's the switching-frequency, could means many wakee or
>> + * rapidly switch, use factor here will just help to automatically
>> + * adjust the loose-degree, so bigger node will lead to more pull.
>> + */
>> + if (p->nr_wakee_switch > factor) {
>> + /*
>> + * wakee is somewhat hot, it needs certain amount of cpu
>> + * resource, so if waker is far more hot, prefer to leave
>> + * it alone.
>> + */
>> + if (current->nr_wakee_switch > (factor * p->nr_wakee_switch))
>> + return 1;
>> + }
>> +
>> + return 0;
>> +}
>
> ---
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 9b1f2e5..166ab9b 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -5081,18 +5083,23 @@ static void destroy_sched_domains(struct sched_domain
> *sd, int cpu)
> * two cpus are in the same cache domain, see cpus_share_cache().
> */
> DEFINE_PER_CPU(struct sched_domain *, sd_llc);
> +DEFINE_PER_CPU(int, sd_llc_size);
> DEFINE_PER_CPU(int, sd_llc_id);
>
> static void update_top_cache_domain(int cpu)
> {
> struct sched_domain *sd;
> int id = cpu;
> + int size = 1;
>
> sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
> - if (sd)
> + if (sd) {
> id = cpumask_first(sched_domain_span(sd));
> + size = cpumask_weight(sched_domain_span(sd));
> + }
>
> rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
> + per_cpu(sd_llc_size, cpu) = size;
> per_cpu(sd_llc_id, cpu) = id;
> }
>
> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> index ef0a7b2..c992f58 100644
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -595,6 +595,7 @@ static inline struct sched_domain
> *highest_flag_domain(int cpu, int flag)
> }
>
> DECLARE_PER_CPU(struct sched_domain *, sd_llc);
> +DECLARE_PER_CPU(int, sd_llc_size);
> DECLARE_PER_CPU(int, sd_llc_id);
>
> struct sched_group_power {
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -3175,7 +3175,7 @@ static inline unsigned long effective_lo
>
> static int wake_wide(struct task_struct *p)
> {
> - int factor = nr_cpus_node(cpu_to_node(smp_processor_id()));
> + int factor = this_cpu_read(sd_llc_size);
>
> /*
> * Yeah, it's the switching-frequency, could means many wakee or
>
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