v6: - [v5] https://lore.kernel.org/lkml/20230713172601.3285847-1-longman@xxxxxxxxxx/ - Add another read-only cpuset.cpus.exclusive.effective control file to expose the effective set of exclusive CPUs. - Update the documentation and test accordingly. v5: - [v4] https://lore.kernel.org/lkml/20230627143508.1576882-1-longman@xxxxxxxxxx/ - Drop the first 4 patches as they had been merged. - Make cpuset.cpus.exclusive invariant once it is manually set. This also means the cpuset.cpus.exclusive may not show the effective value that is actually being used. - Update the documentation and test accordingly. v4: - [v3] https://lore.kernel.org/lkml/20230627005529.1564984-1-longman@xxxxxxxxxx/ - Fix compilation problem reported by kernel test robot. This patch series introduces new cpuset control files "cpuset.cpus.exclusive" (read-write) and "cpuset.cpus.exclusive.effective" (read only) for better control of which exclusive CPUs are being distributed down the cgroup hierarchy for creating cpuset partition. Any one of the exclusive CPUs can only be distributed to at most one child cpuset. Invalid input to "cpuset.cpus.exclusive" that violates the sibling exclusivity rule will be rejected. This new control files has no effect on the behavior of the cpuset until it turns into a partition root. At that point, its effective CPUs will be set to its exclusive CPUs unless some of them are offline. This patch series also introduces a new category of cpuset partition called remote partitions. The existing partition category where the partition roots have to be clustered around the root cgroup in a hierarchical way is now referred to as local partitions. A remote partition can be formed far from the root cgroup with no partition root parent. While local partitions can be created without touching "cpuset.cpus.exclusive" as it can be set automatically if a cpuset becomes a local partition root. Properly setting "cpuset.cpus.exclusive" values down the hierarchy are required to create a remote partition. Both scheduling and isolated partitions can be formed as a remote partition. A local partition can be created under a remote partition. A remote partition, however, cannot be formed under a local partition for now. Modern container orchestration tools like Kubernetes use the cgroup hierarchy to manage different containers. And it is relying on other middleware like systemd to help managing it. If a container needs to use isolated CPUs, it is hard to get those with the local partitions as it will require the administrative parent cgroup to be a partition root too which tool like systemd may not be ready to manage. With this patch series, we allow the creation of remote partition far from the root. The container management tool can manage the "cpuset.cpus.exclusive" file without impacting the other cpuset files that are managed by other middlewares. Of course, invalid "cpuset.cpus.exclusive" values will be rejected. Waiman Long (6): cgroup/cpuset: Add cpuset.cpus.exclusive.effective for v2 cgroup/cpuset: Add cpuset.cpus.exclusive for v2 cgroup/cpuset: Introduce remote partition cgroup/cpuset: Check partition conflict with housekeeping setup cgroup/cpuset: Documentation update for partition cgroup/cpuset: Extend test_cpuset_prs.sh to test remote partition Documentation/admin-guide/cgroup-v2.rst | 123 +- kernel/cgroup/cpuset.c | 1283 +++++++++++++---- .../selftests/cgroup/test_cpuset_prs.sh | 428 ++++-- 3 files changed, 1343 insertions(+), 491 deletions(-) -- 2.31.1
