Re: [PATCH v10 08/11] sched: replace capacity_factor by usage

Hi Vincent,

On 27 February 2015 at 23:54, Vincent Guittot vincent.guittot@linaro.org wrote:

/** @@ -6432,18 +6435,19 @@ static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sd

            /*
             * In case the child domain prefers tasks go to siblings

•            * first, lower the sg capacity factor to one so that we'll try
  

•            * first, lower the sg capacity so that we'll try
             * and move all the excess tasks away. We lower the capacity
             * of a group only if the local group has the capacity to fit
  

•            * these excess tasks, i.e. nr_running < group_capacity_factor. The
  

•            * extra check prevents the case where you always pull from the
  

•            * heaviest group when it is already under-utilized (possible
  

•            * with a large weight task outweighs the tasks on the system).
  

•            * these excess tasks. The extra check prevents the case where
  

•            * you always pull from the heaviest group when it is already
  

•            * under-utilized (possible with a large weight task outweighs
  

•            * the tasks on the system).
             */
            if (prefer_sibling && sds->local &&
  

•               sds->local_stat.group_has_free_capacity) {
  

•                   sgs->group_capacity_factor = min(sgs->group_capacity_factor, 1U);
  

•                   sgs->group_type = group_classify(sg, sgs);
  

•               group_has_capacity(env, &sds->local_stat) &&
  

•               (sgs->sum_nr_running > 1)) {
  

•                   sgs->group_no_capacity = 1;
  

•                   sgs->group_type = group_overloaded;
            }
  
  

For SD_PREFER_SIBLING, if local has 1 task and group_has_capacity() returns true(but not overloaded) for it, and assume sgs group has 2 tasks, should we still mark this group overloaded?

-Xunlei