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

[Dietmar Eggemann]

On 30/05/14 20:20, Vincent Guittot wrote:
> On 30 May 2014 11:50, Dietmar Eggemann <dietmar.eggemann@xxxxxxx> 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@xxxxxxxxxx>
> >
> > [...]
> >
> > >   /*
> > >    * 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().

[...]


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