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sched/fair: Revise comment about lb decision matrix

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If busiest group type is group_misfit_task, the local
group type must be group_has_spare according to below
code in update_sd_pick_busiest():

  if (sgs->group_type == group_misfit_task &&
      (!capacity_greater(capacity_of(env->dst_cpu), sg->sgc->max_capacity) ||
       sds->local_stat.group_type != group_has_spare))
	   return false;

group type imbalanced and overloaded and fully_busy are filtered in here.
misfit and asym are filtered before in update_sg_lb_stats().
So, change the decision matrix to:

  busiest \ local has_spare fully_busy misfit asym imbalanced overloaded
  has_spare        nr_idle   balanced   N/A    N/A  balanced   balanced
  fully_busy       nr_idle   nr_idle    N/A    N/A  balanced   balanced
  misfit_task      force     N/A        N/A    N/A  *N/A*      *N/A*
  asym_packing     force     force      N/A    N/A  force      force
  imbalanced       force     force      N/A    N/A  force      force
  overloaded       force     force      N/A    N/A  force      avg_load

Fixes: 0b0695f2b3 ("sched/fair: Rework load_balance()")
Signed-off-by: Tao Zhou <tao.zhou@linux.dev>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20220415095505.7765-1-tao.zhou@linux.dev
This commit is contained in:
Tao Zhou 2022-04-15 17:55:04 +08:00 committed by Peter Zijlstra
parent 890d550d7d
commit a658353167
1 changed files with 1 additions and 1 deletions

2
kernel/sched/fair.c
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@ -9496,7 +9496,7 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s
* busiest \ local has_spare fully_busy misfit asym imbalanced overloaded
* has_spare nr_idle balanced N/A N/A balanced balanced
* fully_busy nr_idle nr_idle N/A N/A balanced balanced
* misfit_task force N/A N/A N/A force force
* misfit_task force N/A N/A N/A N/A N/A
* asym_packing force force N/A N/A force force
* imbalanced force force N/A N/A force force
* overloaded force force N/A N/A force avg_load