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    Subject[PATCH v11 6/9] cpuset: Make generate_sched_domains() recognize reserved_cpus
    Date
    The generate_sched_domains() function is modified to make it work
    correctly with the newly introduced reserved_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 e118dd8..e545848 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.nr_reserved) {
    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 partition root */
    + if (!is_partition_root(cp))
    + pos_css = css_rightmost_descendant(pos_css);
    }
    rcu_read_unlock();

    @@ -850,7 +861,12 @@ 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.nr_reserved &&
    + !cpumask_equal(top_cpuset.effective_cpus, cpu_active_mask))
    + goto out;
    +
    + if (top_cpuset.nr_reserved &&
    + !cpumask_subset(top_cpuset.effective_cpus, cpu_active_mask))
    goto out;

    /* Generate domain masks and attrs */
    --
    1.8.3.1
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