Re: [PATCH v10 6/9] cpuset: Make generate_sched_domains() recognize isolated_cpus

Waiman Long
2018-06-18T14:44:55Z

On 06/18/2018 12:14 PM, Waiman Long wrote:
> The generate_sched_domains() function and the hotplug code are modified
> to make them use the newly introduced isolated_cpus mask for schedule
> domains generation.
>
> Signed-off-by: Waiman Long <longman@redhat.com>
> ---
> kernel/cgroup/cpuset.c | 24 ++++++++++++++++++++----
> 1 file changed, 20 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index cfc9b7b..5ee4239 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -672,13 +672,14 @@ static int generate_sched_domains(cpumask_var_t **domains,
> int ndoms = 0; /* number of sched domains in result */
> int nslot; /* next empty doms[] struct cpumask slot */
> struct cgroup_subsys_state *pos_css;
> + bool root_load_balance = is_sched_load_balance(&top_cpuset);
>
> doms = NULL;
> dattr = NULL;
> csa = NULL;
>
> /* Special case for the 99% of systems with one, full, sched domain */
> - if (is_sched_load_balance(&top_cpuset)) {
> + if (root_load_balance && !top_cpuset.isolation_count) {
> ndoms = 1;
> doms = alloc_sched_domains(ndoms);
> if (!doms)
> @@ -701,6 +702,8 @@ static int generate_sched_domains(cpumask_var_t **domains,
> csn = 0;
>
> rcu_read_lock();
> + if (root_load_balance)
> + csa[csn++] = &top_cpuset;
> cpuset_for_each_descendant_pre(cp, pos_css, &top_cpuset) {
> if (cp == &top_cpuset)
> continue;
> @@ -711,6 +714,9 @@ static int generate_sched_domains(cpumask_var_t **domains,
> * parent's cpus, so just skip them, and then we call
> * update_domain_attr_tree() to calc relax_domain_level of
> * the corresponding sched domain.
> + *
> + * If root is load-balancing, we can skip @cp if it
> + * is a subset of the root's effective_cpus.
> */
> if (!cpumask_empty(cp->cpus_allowed) &&
> !(is_sched_load_balance(cp) &&
> @@ -718,11 +724,16 @@ static int generate_sched_domains(cpumask_var_t **domains,
> housekeeping_cpumask(HK_FLAG_DOMAIN))))
> continue;
>
> + if (root_load_balance &&
> + cpumask_subset(cp->cpus_allowed, top_cpuset.effective_cpus))
> + continue;
> +
> if (is_sched_load_balance(cp))
> csa[csn++] = cp;
>
> - /* skip @cp's subtree */
> - pos_css = css_rightmost_descendant(pos_css);
> + /* skip @cp's subtree if not a scheduling domain root */
> + if (!is_sched_domain_root(cp))
> + pos_css = css_rightmost_descendant(pos_css);
> }
> rcu_read_unlock();
>
> @@ -849,7 +860,12 @@ static void rebuild_sched_domains_locked(void)
> * passing doms with offlined cpu to partition_sched_domains().
> * Anyways, hotplug work item will rebuild sched domains.
> */
> - if (!cpumask_equal(top_cpuset.effective_cpus, cpu_active_mask))
> + if (!top_cpuset.isolation_count &&
> + !cpumask_equal(top_cpuset.effective_cpus, cpu_active_mask))
> + goto out;
> +
> + if (top_cpuset.isolation_count &&
> + !cpumask_subset(top_cpuset.effective_cpus, cpu_active_mask))
> goto out;
>
> /* Generate domain masks and attrs */

Sorry, that one is bogus. Please ignore that.

NAK