On 04/28/2017 10:53 AM, Peter Zijlstra wrote:
> On Fri, Apr 28, 2017 at 03:19:58PM +0200, Peter Zijlstra wrote:
>> Hi,
>>
>> These patches are based upon the hard work of Lauro. He put in the time and
>> effort to understand and debug the code.
>>
>> So while I didn't take many of his actual patches; I want to thank him for
>> doing the work. Hopefully the "Debugged-by:" tag conveys some of that.
>>
>> In any case, please have a look. I think these should about cover things.
>>
>> Rik, Lauro, could you guys in particular look at the final patch that adds a
>> few comments. I attempted to document the intent and understanding there. But
>> given I've been staring at this stuff too long I could've missed the obvious.
>>
>> Comments and or suggestions welcome.
>>
> Also, the following occurred to me:
>
> sg_span & sg_mask == sg_mask
>
> Therefore, we don't need to do the whole "sg_span &" business.
>
> Hmm?
Agreed. Maybe we have to rename "mask" to something else. Maybe
"group_reached_by_cpus" or "group_installed_on_cpus".
>
> ---
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -7996,7 +7996,7 @@ static int active_load_balance_cpu_stop(
> static int should_we_balance(struct lb_env *env)
> {
> struct sched_group *sg = env->sd->groups;
> - struct cpumask *sg_cpus, *sg_mask;
> + struct cpumask *sg_mask;
> int cpu, balance_cpu = -1;
>
> /*
> @@ -8006,11 +8006,10 @@ static int should_we_balance(struct lb_e
> if (env->idle == CPU_NEWLY_IDLE)
> return 1;
>
> - sg_cpus = sched_group_cpus(sg);
> sg_mask = sched_group_mask(sg);
> /* Try to find first idle cpu */
> - for_each_cpu_and(cpu, sg_cpus, env->cpus) {
> - if (!cpumask_test_cpu(cpu, sg_mask) || !idle_cpu(cpu))
> + for_each_cpu_and(cpu, sg_mask, env->cpus) {
> + if (!idle_cpu(cpu))
> continue;
>
> balance_cpu = cpu;
> --- a/kernel/sched/topology.c
> +++ b/kernel/sched/topology.c
> @@ -85,7 +85,8 @@ static int sched_domain_debug_one(struct
> group->sgc->id,
> cpumask_pr_args(sched_group_cpus(group)));
>
> - if ((sd->flags & SD_OVERLAP) &&
> !cpumask_full(sched_group_mask(group))) {
> + if ((sd->flags & SD_OVERLAP) &&
> + !cpumask_equal(sched_group_mask(group),
> sched_group_cpus(group))) {
> printk(KERN_CONT " mask=%*pbl",
> cpumask_pr_args(sched_group_mask(group)));
> }
> @@ -505,7 +506,7 @@ enum s_alloc {
> */
> int group_balance_cpu(struct sched_group *sg)
> {
> - return cpumask_first_and(sched_group_cpus(sg), sched_group_mask(sg));
> + return cpumask_first(sched_group_mask(sg));
> }
>
>
> @@ -856,7 +857,7 @@ build_sched_groups(struct sched_domain *
> continue;
>
> group = get_group(i, sdd, &sg);
> - cpumask_setall(sched_group_mask(sg));
> + cpumask_copy(sched_group_mask(sg), sched_group_cpus(sg));
>
> for_each_cpu(j, span) {
> if (get_group(j, sdd, NULL) != group)
