On Tue, 2013-03-26 at 15:01 +0900, Joonsoo Kim wrote: > Commit 88b8dac0 makes load_balance() consider other cpus in its group. > But, in that, there is no code for preventing to re-select dst-cpu. > So, same dst-cpu can be selected over and over. > > This patch add functionality to load_balance() in order to exclude > cpu which is selected once. We prevent to re-select dst_cpu via > env's cpus, so now, env's cpus is a candidate not only for src_cpus, > but also dst_cpus.
Changelog forgets to mention that this removes the need for lb_iterations. > Cc: Srivatsa Vaddagiri <[email protected]> > Signed-off-by: Joonsoo Kim <[email protected]> > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index e3f09f4..6f238d2 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -3898,12 +3898,14 @@ int can_migrate_task(struct task_struct *p, struct > lb_env *env) > if (!env->dst_grpmask || (env->flags & LBF_SOME_PINNED)) > return 0; > > - new_dst_cpu = cpumask_first_and(env->dst_grpmask, > - tsk_cpus_allowed(p)); > - if (new_dst_cpu < nr_cpu_ids) { > - env->flags |= LBF_SOME_PINNED; > - env->new_dst_cpu = new_dst_cpu; > - } > + /* Prevent to re-select dst_cpu via env's cpus */ > + for_each_cpu_and(cpu, env->dst_grpmask, env->cpus) > + if (cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) { > + env->flags |= LBF_SOME_PINNED; > + env->new_dst_cpu = cpu; > + break; > + } /me hands you a fresh bucket of curlies.. always use them on multi-line single statements. > return 0; > } > > @@ -4989,7 +4991,6 @@ static int load_balance(int this_cpu, struct rq > *this_rq, > int *balance) > { > int ld_moved, cur_ld_moved, active_balance = 0; > - int lb_iterations, max_lb_iterations; > struct sched_group *group; > struct rq *busiest; > unsigned long flags; > @@ -5009,11 +5010,6 @@ static int load_balance(int this_cpu, struct rq > *this_rq, > * other cpus in our group */ > if (idle == CPU_NEWLY_IDLE) { > env.dst_grpmask = NULL; > - /* we don't care max_lb_iterations in this case, > - * in following patch, this will be removed */ > - max_lb_iterations = 0; > - } else { > - max_lb_iterations = cpumask_weight(env.dst_grpmask); > } And here you leave curlies around a single line single statement (the only case we do leave them off) -- maybe collect them to replenish your supply? > cpumask_copy(cpus, cpu_active_mask); > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
