[PATCH-cgroup v5 0/6] cgroup/cpuset: Add new cpuset partition type & empty effecitve cpus

Waiman Long
2021-08-14T17:41:36Z

v5:
- Rebased to the latest for-5.15 branch of cgroup git tree and drop the
1st v4 patch as it has been merged.
- Update patch 1 to always allow changing partition root back to member
even if it invalidates child partitions undeneath it.
- Adjust the empty effective cpu partition patch to not allow 0 effective
cpu for terminal partition which will make it invalid).
- Add a new patch to enable reading of cpuset.cpus.partition to display
the reason that causes invalid partition.
- Adjust the documentation and testing patch accordingly.

v4:
- Rebased to the for-5.15 branch of cgroup git tree and dropped the
first 3 patches of v3 series which have been merged.
- Beside prohibiting violation of cpu exclusivity rule, allow arbitrary
changes to cpuset.cpus of a partition root and force the partition root
to become invalid in case any of the partition root constraints
are violated. The documentation file and self test are modified
accordingly.

This patchset makes four enhancements to the cpuset v2 code.

Patch 1: Properly handle partition root tree and make partition
invalid in case changes to cpuset.cpus violate any of the partition
root constraints.

Patch 2: Enable the "cpuset.cpus.partition" file to show the reason
that causes invalid partition like "root invalid (No cpu available
due to hotplug)".

Patch 3: Add a new partition state "isolated" to create a partition
root without load balancing. This is for handling intermitten workloads
that have a strict low latency requirement.

Patch 4: Allow partition roots that are not the top cpuset to distribute
all its cpus to child partitions as long as there is no task associated
with that partition root. This allows more flexibility for middleware
to manage multiple partitions.

Patch 5 updates the cgroup-v2.rst file accordingly. Patch 6 adds a new
cpuset test to test the new cpuset partition code.

Waiman Long (6):
cgroup/cpuset: Properly transition to invalid partition
cgroup/cpuset: Show invalid partition reason string
cgroup/cpuset: Add a new isolated cpus.partition type
cgroup/cpuset: Allow non-top parent partition to distribute out all
CPUs
cgroup/cpuset: Update description of cpuset.cpus.partition in
cgroup-v2.rst
kselftest/cgroup: Add cpuset v2 partition root state test

Documentation/admin-guide/cgroup-v2.rst | 116 +--
kernel/cgroup/cpuset.c | 347 ++++++---
tools/testing/selftests/cgroup/Makefile | 5 +-
.../selftests/cgroup/test_cpuset_prs.sh | 663 ++++++++++++++++++
tools/testing/selftests/cgroup/wait_inotify.c | 86 +++
5 files changed, 1068 insertions(+), 149 deletions(-)
create mode 100755 tools/testing/selftests/cgroup/test_cpuset_prs.sh
create mode 100644 tools/testing/selftests/cgroup/wait_inotify.c

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2.18.1