On 2022-11-12 17:19:39 [-0500], Waiman Long wrote: > It was found that with the default hierarchy, enabling cpuset in the > child cgroups can trigger a cpuset_attach() call in each of the child > cgroups that have tasks with no change in effective cpus and mems. If > there are many processes in those child cgroups, it will burn quite a > lot of cpu cycles iterating all the tasks without doing useful work. Thank you. So this preserves the CPU mask upon attaching the cpuset container. | ~# taskset -pc $$ | pid 1564's current affinity list: 0-2 default mask after boot due to isolcpus= | ~# echo "+cpu" >> /sys/fs/cgroup/cgroup.subtree_control ; echo "+cpuset" >> /sys/fs/cgroup/cgroup.subtree_control | ~# taskset -pc $$ | pid 1564's current affinity list: 0-2 okay. | ~# echo 1-3 > /sys/fs/cgroup/user.slice/cpuset.cpus | ~# taskset -pc $$ | pid 1564's current affinity list: 1-3 wiped away. | ~# taskset -pc 2-3 $$ | pid 1564's current affinity list: 1-3 | pid 1564's new affinity list: 2,3 | ~# echo 2-4 > /sys/fs/cgroup/user.slice/cpuset.cpus | ~# taskset -pc 2-3 $$ | pid 1564's current affinity list: 2,3 | pid 1564's new affinity list: 2,3 But it works if the mask was changed on purpose. Sebastian
