Messages in this thread | | | Date | Thu, 21 Jul 2022 15:29:49 +0100 | From | Qais Yousef <> | Subject | Re: [PATCH 2/7] sched/uclamp: Make task_fits_capacity() use util_fits_cpu() |
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On 07/12/22 11:48, Qais Yousef wrote: > On 07/11/22 15:09, Vincent Guittot wrote: > > On Wed, 29 Jun 2022 at 21:48, Qais Yousef <qais.yousef@arm.com> wrote: > > [...] > > > > @@ -8502,15 +8504,16 @@ static void update_cpu_capacity(struct sched_domain *sd, int cpu) > > > trace_sched_cpu_capacity_tp(cpu_rq(cpu)); > > > > > > sdg->sgc->capacity = capacity; > > > - sdg->sgc->min_capacity = capacity; > > > - sdg->sgc->max_capacity = capacity; > > > + sdg->sgc->min_capacity_cpu = cpu; > > > + sdg->sgc->max_capacity_cpu = cpu; > > > > you make these fields useless. There is only one cpu per sched_group > > at this level so you don't need to save the twice cpu number of the > > nly cpu of this group > > Ah, so we can use group->asym_prefer_cpu then? > > I think I got confused and thought we could cover multiple capacity levels > there. > > > > } > > > > > > void update_group_capacity(struct sched_domain *sd, int cpu) > > > { > > > - struct sched_domain *child = sd->child; > > > struct sched_group *group, *sdg = sd->groups; > > > - unsigned long capacity, min_capacity, max_capacity; > > > + struct sched_domain *child = sd->child; > > > + int min_capacity_cpu, max_capacity_cpu; > > > + unsigned long capacity; > > > unsigned long interval; > > > > > > interval = msecs_to_jiffies(sd->balance_interval); > > > @@ -8523,8 +8526,7 @@ void update_group_capacity(struct sched_domain *sd, int cpu) > > > } > > > > > > capacity = 0; > > > - min_capacity = ULONG_MAX; > > > - max_capacity = 0; > > > + min_capacity_cpu = max_capacity_cpu = cpu; > > > > > > if (child->flags & SD_OVERLAP) { > > > /* > > > @@ -8536,29 +8538,44 @@ void update_group_capacity(struct sched_domain *sd, int cpu) > > > unsigned long cpu_cap = capacity_of(cpu); > > > > > > capacity += cpu_cap; > > > - min_capacity = min(cpu_cap, min_capacity); > > > - max_capacity = max(cpu_cap, max_capacity); > > > + if (cpu_cap < capacity_of(min_capacity_cpu)) > > > + min_capacity_cpu = cpu; > > > + > > > + if (cpu_cap > capacity_of(max_capacity_cpu)) > > > + max_capacity_cpu = cpu; > > > } > > > } else { > > > /* > > > * !SD_OVERLAP domains can assume that child groups > > > * span the current group. > > > */ > > > + unsigned long min_capacity = ULONG_MAX; > > > + unsigned long max_capacity = 0; > > > > > > group = child->groups; > > > do { > > > struct sched_group_capacity *sgc = group->sgc; > > > + unsigned long cpu_cap_min = capacity_of(sgc->min_capacity_cpu); > > > + unsigned long cpu_cap_max = capacity_of(sgc->max_capacity_cpu); > > > > By replacing sgc->min_capacity with sgc->min_capacity_cpu, the > > min_capacity is no more stable and can become > max_capacity > > Right. > > > > > > > > > capacity += sgc->capacity; > > > - min_capacity = min(sgc->min_capacity, min_capacity); > > > - max_capacity = max(sgc->max_capacity, max_capacity); > > > + if (cpu_cap_min < min_capacity) { > > > + min_capacity = cpu_cap_min; > > > + min_capacity_cpu = sgc->min_capacity_cpu; > > > + } > > > + > > > + if (cpu_cap_max > max_capacity) { > > > + max_capacity = cpu_cap_max; > > > + max_capacity_cpu = sgc->max_capacity_cpu; > > > + } > > > + > > > group = group->next; > > > } while (group != child->groups); > > > } > > > > > > sdg->sgc->capacity = capacity; > > > - sdg->sgc->min_capacity = min_capacity; > > > - sdg->sgc->max_capacity = max_capacity; > > > + sdg->sgc->min_capacity_cpu = min_capacity_cpu; > > > + sdg->sgc->max_capacity_cpu = max_capacity_cpu; > > > } > > > > > > /* > > > @@ -8902,7 +8919,7 @@ static bool update_sd_pick_busiest(struct lb_env *env, > > > * internally or be covered by avg_load imbalance (eventually). > > > */ > > > if (sgs->group_type == group_misfit_task && > > > - (!capacity_greater(capacity_of(env->dst_cpu), sg->sgc->max_capacity) || > > > + (!capacity_greater(env->dst_cpu, sg->sgc->max_capacity_cpu) || > > > sds->local_stat.group_type != group_has_spare)) > > > return false; > > > > > > @@ -8986,7 +9003,7 @@ static bool update_sd_pick_busiest(struct lb_env *env, > > > */ > > > if ((env->sd->flags & SD_ASYM_CPUCAPACITY) && > > > (sgs->group_type <= group_fully_busy) && > > > - (capacity_greater(sg->sgc->min_capacity, capacity_of(env->dst_cpu)))) > > > + (capacity_greater(sg->sgc->min_capacity_cpu, env->dst_cpu))) > > > return false; > > > > > > return true; > > > @@ -9108,7 +9125,7 @@ static inline void update_sg_wakeup_stats(struct sched_domain *sd, > > > > > > /* Check if task fits in the group */ > > > if (sd->flags & SD_ASYM_CPUCAPACITY && > > > - !task_fits_capacity(p, group->sgc->max_capacity)) { > > > + !task_fits_cpu(p, group->sgc->max_capacity_cpu)) { > > > > All the changes and added complexity above for this line. Can't you > > find another way ? > > You're right, I might have got carried away trying to keep the logic the same. > > Can we use group->asym_prefer_cpu or pick a cpu from group->sgc->cpumask > instead? > > I'll dig more into it anyway and try to come up with simpler alternative.
Actually we can't.
I can keep the current {max,min}_capacity field and just add the new {max,min}_capacity_cpu and use them where needed. Should address your concerns this way? That was actually the first version of the code, but then it seemed redundant to keep both {max,min}_capacity and {max,min}_capacity_cpu.
OR
I can add a new function to search for max spare capacity cpu in the group.
Preference?
Thanks!
-- Qais Yousef
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