On Thu, 2013-02-14 at 14:48 +0900, Joonsoo Kim wrote:
> Commit 88b8dac0 makes load_balance() consider other cpus in its group.
> So, now, When we redo in load_balance(), we should reset some fields of
> lb_env to ensure that load_balance() works for initial cpu, not for other
> cpus in its group. So correct it.
>
> Cc: Srivatsa Vaddagiri <va...@linux.vnet.ibm.com>
> Signed-off-by: Joonsoo Kim <iamjoonsoo....@lge.com>
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 70631e8..25c798c 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -5014,14 +5014,20 @@ static int load_balance(int this_cpu, struct rq
> *this_rq,
>
> struct lb_env env = {
> .sd = sd,
> - .dst_cpu = this_cpu,
> - .dst_rq = this_rq,
> .dst_grpmask = dst_grp,
> .idle = idle,
> - .loop_break = sched_nr_migrate_break,
> .cpus = cpus,
> };
>
> + schedstat_inc(sd, lb_count[idle]);
> + cpumask_copy(cpus, cpu_active_mask);
> +
> +redo:
> + env.dst_cpu = this_cpu;
> + env.dst_rq = this_rq;
> + env.loop = 0;
> + env.loop_break = sched_nr_migrate_break;
> +
> /* For NEWLY_IDLE load_balancing, we don't need to consider
> * other cpus in our group */
> if (idle == CPU_NEWLY_IDLE) {
OK, so this is the case where we tried to balance !this_cpu and found
ALL_PINNED, right?
You can only get here in very weird cases where people love their
sched_setaffinity() waaaaay too much, do we care? Why not give up?
Also, looking at this, shouldn't we consider env->cpus in
can_migrate_task() where we compute new_dst_cpu?
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