On 30/05/14 20:20, Vincent Guittot wrote:
> On 30 May 2014 11:50, Dietmar Eggemann <dietmar.eggemann at arm.com> wrote:
>> On 23/05/14 16:53, Vincent Guittot wrote:
>>> Monitor the activity level of each group of each sched_domain level. The
>>> activity is the amount of cpu_power that is currently used on a CPU or group
>>> of CPUs. We use the runnable_avg_sum and _period to evaluate this activity
>>> level. In the special use case where the CPU is fully loaded by more than 1
>>> task, the activity level is set above the cpu_power in order to reflect the
>>> overload of the CPU
>>>
>>> Signed-off-by: Vincent Guittot <vincent.guittot at linaro.org>
>>
>> [...]
>>
>>> /*
>>> * select_task_rq_fair: Select target runqueue for the waking task in domains
>>> * that have the 'sd_flag' flag set. In practice, this is SD_BALANCE_WAKE,
>>> @@ -5518,6 +5535,7 @@ struct sg_lb_stats {
>>> unsigned long sum_weighted_load; /* Weighted load of group's tasks */
>>> unsigned long load_per_task;
>>> unsigned long group_power;
>>> + unsigned long group_activity; /* Total activity of the group */
>>> unsigned int sum_nr_running; /* Nr tasks running in the group */
>>> unsigned int group_capacity;
>>> unsigned int idle_cpus;
>>> @@ -5538,6 +5556,7 @@ struct sd_lb_stats {
>>> struct sched_group *busiest; /* Busiest group in this sd */
>>> struct sched_group *local; /* 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 */
>>>
>>> @@ -5557,6 +5576,7 @@ static inline void init_sd_lb_stats(struct sd_lb_stats *sds)
>>> .busiest = NULL,
>>> .local = NULL,
>>> .total_load = 0UL,
>>> + .total_activity = 0UL,
>>
>> AFAICS, total_activity is not used right now. Do you intend to use it to
>> calculate something like avg_activity later (like total_load/avg_load)?
>
> this patch only creates group_activity and total_activity.The use of
> these statistics appears on the next patches. I have not planned to
> compute such avg_activity for the moment mainly because i have need it
> yet.
>
> Do you have in mind any use of such avg_activity ?
No, not really but I still don't see (taken all your patches) where
sds->total_activity is used.
$ find . -name "*.[ch]" | xargs grep total_activity
./kernel/sched/fair.c: unsigned long total_activity; /* Total activity
of all groups in sd */
./kernel/sched/fair.c: .total_activity = 0UL,
./kernel/sched/fair.c: sds->total_activity += sgs->group_activity;
OOTH, sgs->group_activity is used to set sgs->group_capacity which is
then used in if conditions in update_sd_pick_busiest(),
update_sd_lb_stats() and find_busiest_group().
[...]