On 27 March 2015 at 15:52, Xunlei Pang <pang.xun...@linaro.org> wrote:
> Hi Vincent,
>
> On 27 February 2015 at 23:54, Vincent Guittot
> <vincent.guit...@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?
yes, the load balance will then choose if it's worth pulling it or not
depending of the load of each groups
>
> -Xunlei
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