Re: [RFC 5/6] sched: pack the idle load balance

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

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 ?

• 	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" ?

Regards santosh