On 2025/12/25 15:30, Waiman Long wrote:
> If exclusive_cpus is set, effective_xcpus must be a subset of
> exclusive_cpus. Currently, rm_siblings_excl_cpus() checks both
> exclusive_cpus and effective_xcpus connectively. It is simpler
> to check only exclusive_cpus if non-empty or just effective_xcpus
> otherwise.
>
> No functional change is expected.
>
> Signed-off-by: Waiman Long <[email protected]>
> ---
> kernel/cgroup/cpuset.c | 17 +++++++++--------
> 1 file changed, 9 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index 221da921b4f9..3d2d28f0fd03 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -1355,23 +1355,24 @@ static int rm_siblings_excl_cpus(struct cpuset
> *parent, struct cpuset *cs,
> int retval = 0;
>
> if (cpumask_empty(excpus))
> - return retval;
> + return 0;
>
> /*
> * Exclude exclusive CPUs from siblings
> */
> rcu_read_lock();
> cpuset_for_each_child(sibling, css, parent) {
> + struct cpumask *sibling_xcpus;
> +
> if (sibling == cs)
> continue;
>
> - if (cpumask_intersects(excpus, sibling->exclusive_cpus)) {
> - cpumask_andnot(excpus, excpus, sibling->exclusive_cpus);
> - retval++;
> - continue;
> - }
> - if (cpumask_intersects(excpus, sibling->effective_xcpus)) {
> - cpumask_andnot(excpus, excpus,
> sibling->effective_xcpus);
> + sibling_xcpus = cpumask_empty(sibling->exclusive_cpus)
> + ? sibling->effective_xcpus
> + : sibling->exclusive_cpus;
> +
I'm wondering if this is sufficient?
sibling_xcpus = sibling->effective_xcpus
p(exclusive_cpus = 1)
/ \
a b(root, exclusive_cpus=1-7, effective_xcpus=1)
What the sibling's effective exclusive CPUs actually should be is not CPUs 1-7
but CPU 1. So, do we
need to remove CPUs 2-7?
> + if (cpumask_intersects(excpus, sibling_xcpus)) {
> + cpumask_andnot(excpus, excpus, sibling_xcpus);
> retval++;
> }
> }
--
Best regards,
Ridong
