On Tue, Mar 19, 2013 at 03:30:15PM +0100, Peter Zijlstra wrote: > On Thu, 2013-02-14 at 14:48 +0900, Joonsoo Kim wrote: > > Some validation for task moving is performed in move_tasks() and > > move_one_task(). We can move these code to can_migrate_task() > > which is already exist for this purpose. > > > @@ -4011,18 +4027,7 @@ static int move_tasks(struct lb_env *env) > > break; > > } > > > > - if (throttled_lb_pair(task_group(p), env->src_cpu, > > env->dst_cpu)) > > - goto next; > > - > > - load = task_h_load(p); > > - > > - if (sched_feat(LB_MIN) && load < 16 && > > !env->sd->nr_balance_failed) > > - goto next; > > - > > - if ((load / 2) > env->imbalance) > > - goto next; > > - > > - if (!can_migrate_task(p, env)) > > + if (!can_migrate_task(p, env, false, &load)) > > goto next; > > > > move_task(p, env); > > Right, so I'm not so taken with this one. The whole load stuff really > is a balance heuristic that's part of move_tasks(), move_one_task() > really doesn't care about that. > > So why did you include it? Purely so you didn't have to re-order the > tests? I don't see any reason not to flip a tests around.
I think that I'm not fully understand what you are concerning, because of my poor English. If possible, please elaborate on a problem in more detail. First of all, I do my best to answer your question. Patch 4/8, 5/8 are for mitigating useless redoing overhead caused by LBF_ALL_PINNED. For this purpose, we should check 'cpu affinity' before evaluating a load. Just moving up can_migrate_task() above load evaluation code may raise side effect, because can_migrate_task() have other checking which is 'cache hottness'. I don't want a side effect. So embedding load evaluation to can_migrate_task() and re-order checking and makes load evaluation disabled for move_one_task(). If your recommandation is to move up can_mirate_task() above load evaluation code, yes, I can, and will do that. :) Please let me know what I am misunderstand. Thanks. > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
