Messages in this thread | | | Date | Sun, 17 Sep 2023 12:51:43 -0400 | Subject | Re: [PATCH 1/1] cgroup/cpuset: Rebuild sched domains if isolated partition changed | From | Waiman Long <> |
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On 9/15/23 11:45, Pierre Gondois wrote: > When an isolated parition is created, the sched domains (sds) are > rebuilt and the sds of the isolated CPUs are detached. This only > happens at the creation of the isolated parition. Updating > the cpuset of the partition doesn't rebuild the sds: > > To reproduce: > # ls /sys/kernel/debug/sched/domains/cpu0/ > domain0 > # ls /sys/kernel/debug/sched/domains/cpu1/ > domain0 > # > # mkdir cgroup > # mount -t cgroup2 none cgroup/ > # mkdir cgroup/A1/ > # echo "+cpuset" > cgroup/cgroup.subtree_control > # echo 0-3 > cgroup/A1/cpuset.cpus > # echo isolated > cgroup/A1/cpuset.cpus.partition > # > # ls /sys/kernel/debug/sched/domains/cpu0/ > # ls /sys/kernel/debug/sched/domains/cpu1/ > # > # echo 0 > cgroup/A1/cpuset.cpus > # ls /sys/kernel/debug/sched/domains/cpu0/ > # ls /sys/kernel/debug/sched/domains/cpu1/ > # > > Here CPU1 should have a sched domain re-attached. > > Signed-off-by: Pierre Gondois <pierre.gondois@arm.com> > --- > kernel/cgroup/cpuset.c | 12 ++++++++---- > 1 file changed, 8 insertions(+), 4 deletions(-) > > diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c > index 58e6f18f01c1..e3eb27ff9b68 100644 > --- a/kernel/cgroup/cpuset.c > +++ b/kernel/cgroup/cpuset.c > @@ -1680,11 +1680,15 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp, > * empty cpuset is changed, we need to rebuild sched domains. > * On default hierarchy, the cpuset needs to be a partition > * root as well. > + * Also rebuild sched domains if the cpuset of an isolated > + * partition changed. > */ > - if (!cpumask_empty(cp->cpus_allowed) && > - is_sched_load_balance(cp) && > - (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) || > - is_partition_valid(cp))) > + if ((!cpumask_empty(cp->cpus_allowed) && > + is_sched_load_balance(cp) && > + (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) || > + is_partition_valid(cp))) || > + (cp->partition_root_state == PRS_ISOLATED || > + cp->partition_root_state == PRS_INVALID_ISOLATED)) > need_rebuild_sched_domains = true; > > rcu_read_lock();
Thanks for spotting the problem and sending out a patch to fix it. However, it should be done in the update_cpumask(). The sched_domain rebuild in update_cpumasks_hier() is supposed to be used for impacted descendant cpusets lower down in the hierarchy.
Anyway, I believe this problem should have been fixed in commit a86ce68078b2 ("cgroup/cpuset: Extract out CS_CPU_EXCLUSIVE & CS_SCHED_LOAD_BALANCE handling") recently merged into the v6.6 kernel. Would you mind testing the latest upstream kernel to see if this problem is gone or not?
Thanks, Longman
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