Re: [PATCH 09/14] sched: evaluate the activity level of the system

On Thu, Apr 25, 2013 at 06:23:25PM +0100, Vincent Guittot wrote:

We evaluate the activity level of CPUs, groups and domains in order to define how many CPUs are required to handle the current activity.

Signed-off-by: Vincent Guittot vincent.guittot@linaro.org

kernel/sched/fair.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 954adfd..234ecdd 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -3465,7 +3465,22 @@ static int check_pack_buddy(int cpu, struct task_struct *p) return true; return false; +}

+static int get_cpu_activity(int cpu) +{

• struct rq *rq = cpu_rq(cpu);
• u32 sum = rq->avg.runnable_avg_sum;
• u32 period = rq->avg.runnable_avg_period;
• sum = min(sum, period);
• if (sum == period) {

• u32 overload = rq->nr_running > 1 ? 1 : 0;
  

• return power_of(cpu) + overload;
  

• }

Adding one to indicate cpu overload seems to work well in the cases that I can think of. It may take some time to have effect if the overloaded cpu is in a group with nearly overloaded cpus. Adding one won't enable more cpus in another group until they have all reached overload.

Reaching sum == period takes quite a long time. Would it be an idea to use sum*1024 >= period*1000 like you do in is_buddy_full()?

I think that would be more consistent since overloaded is essential the same as full.

Cheers, Morten

• return (sum * power_of(cpu)) / period;

} /* @@ -4355,6 +4370,7 @@ struct sd_lb_stats { struct sched_group *busiest; /* Busiest group in this sd */ struct sched_group *this; /* Local group in this sd */ unsigned long total_load; /* Total load of all groups in sd */

• unsigned long total_activity; /* Total activity of all groups in sd */ unsigned long total_pwr; /* Total power of all groups in sd */ unsigned long avg_load; /* Average load across all groups in sd */

@@ -4383,6 +4399,7 @@ struct sd_lb_stats { struct sg_lb_stats { unsigned long avg_load; /*Avg load across the CPUs of the group */ unsigned long group_load; /* Total load over the CPUs of the group */

• unsigned long group_activity; /* Total activity of the group */ unsigned long sum_nr_running; /* Nr tasks running in the group */ unsigned long sum_weighted_load; /* Weighted load of group's tasks */ unsigned long group_capacity;

@@ -4629,6 +4646,7 @@ static inline void update_sg_lb_stats(struct lb_env *env, } sgs->group_load += load;

• sgs->group_activity += get_cpu_activity(i);
  

  sgs->sum_nr_running += nr_running; sgs->sum_weighted_load += weighted_cpuload(i); if (idle_cpu(i))

@@ -4752,6 +4770,7 @@ static inline void update_sd_lb_stats(struct lb_env *env, return; sds->total_load += sgs.group_load;

• sds->total_activity += sgs.group_activity;
  

  sds->total_pwr += sg->sgp->power;

/* -- 1.7.9.5