Re: [RFC][PATCH 1/5] sched, fair: Let minimally loaded cpu balancethe group

From: Srivatsa Vaddagiri
Date: Wed May 02 2012 - 06:25:50 EST


* Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> [2012-05-01 20:14:31]:

> @@ -3795,12 +3796,11 @@ static inline void update_sg_lb_stats(st
>
> /* Bias balancing toward cpus of our domain */
> if (local_group) {
> - if (idle_cpu(i) && !first_idle_cpu) {
> - first_idle_cpu = 1;
> + load = target_load(i, load_idx);
> + if (load < balance_load || idle_cpu(i)) {
> + balance_load = load;

Let's say load_idx != 0 (ex: a busy cpu doing this load balance). In
that case, for a idle cpu, we could return non-zero load and hence this
would fail to select such a idle cpu? IOW :

balance_load = 0 iff idle_cpu(i) ??

> balance_cpu = i;
> }
> -
> - load = target_load(i, load_idx);
> } else {
> load = source_load(i, load_idx);
> if (load > max_cpu_load) {
>
>

- vatsa

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