[PATCH v2 08/11] sched: get CPU's activity statistic

[Vincent Guittot]

On 1 June 2014 13:33, Dietmar Eggemann <dietmar.eggemann at arm.com> wrote:
> 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().

Sorry, i misread you 1st email and haven't understood that you were
specifically speaking about total_activity.
When i created the activity statistic, i have added both sg and sd
fields but i finally only use the sg one. If i don't need the sd field
after updating my patches, i will remove it

Thanks
Vincent

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