[PATCH v8 0/6] Enable cpuset controller in default hierarchy

[Waiman Long]

v8:
 - Remove cpuset.cpus.isolated and add a new cpuset.sched.domain flag
   and rework the code accordingly.

v7:
 - Add a root-only cpuset.cpus.isolated control file for CPU isolation.
 - Enforce that load_balancing can only be turned off on cpusets with
   CPUs from the isolated list.
 - Update sched domain generation to allow cpusets with CPUs only
   from the isolated CPU list to be in separate root domains.

v6:
 - Hide cpuset control knobs in root cgroup.
 - Rename effective_cpus and effective_mems to cpus.effective and
   mems.effective respectively.
 - Remove cpuset.flags and add cpuset.sched_load_balance instead
   as the behavior of sched_load_balance has changed and so is
   not a simple flag.
 - Update cgroup-v2.txt accordingly.

v5:
 - Add patch 2 to provide the cpuset.flags control knob for the
   sched_load_balance flag which should be the only feature that is
   essential as a replacement of the "isolcpus" kernel boot parameter.

v4:
 - Further minimize the feature set by removing the flags control knob.

v3:
 - Further trim the additional features down to just memory_migrate.
 - Update Documentation/cgroup-v2.txt.

v6 patch: https://lkml.org/lkml/2018/3/21/530
v7 patch: https://lkml.org/lkml/2018/4/19/448

The purpose of this patchset is to provide a basic set of cpuset control
files for cgroup v2. This basic set includes the non-root "cpus",
"mems", "sched.load_balance" and "sched.domain". The "cpus.effective"
and "mems.effective" will appear in all cpuset-enabled cgroups.

The new control file that is unique to v2 is "sched.domain". It is a
boolean flag file that designates if a cgroup is a scheduling domain
with its own set of unique list of CPUs from scheduling perspective
disjointed from other scheduling domains. The root cgroup is always a
scheduling domain. Multiple levels of scheduling domains are supported
with some limitations. So a container scheduling domain root can behave
like a real root.

When a scheduling domain cgroup is removed, its list of exclusive CPUs
will be returned to the parent's cpus.effective automatically.

The "sched.load_balance" flag can only be changed in a scheduling domain.
with no child cpuset-enabled cgroups.

This patchset supports isolated CPUs in a child scheduling domain with
load balancing off. It also allows easy setup of multiple scheduling
domains without requiring the trick of turning load balancing off in the
root cgroup.

This patchset does not exclude the possibility of adding more features
in the future after careful consideration.

Patch 1 enables cpuset in cgroup v2 with cpus, mems and their
effective counterparts.

Patch 2 adds a new "sched.domain" control file for setting up multiple
scheduling domains. A scheduling domain implies cpu_exclusive.

Patch 3 adds a "sched.load_balance" flag to turn off load balancing in
a scheduling domain.

Patch 4 updates the scheduling domain genaration code to work with
the new scheduling domain feature.

Patch 5 exposes cpus.effective and mems.effective to the root cgroup as
enabling child scheduling domains will take CPUs away from the root cgroup.
So it will be nice to monitor what CPUs are left there.

Patch 6 enables the printing the debug information about scheduling
domain generation.

Waiman Long (6):
  cpuset: Enable cpuset controller in default hierarchy
  cpuset: Add new v2 cpuset.sched.domain flag
  cpuset: Add cpuset.sched.load_balance flag to v2
  cpuset: Make generate_sched_domains() recognize isolated_cpus
  cpuset: Expose cpus.effective and mems.effective on cgroup v2 root
  cpuset: Allow reporting of sched domain generation info

 Documentation/cgroup-v2.txt | 136 +++++++++++++++-
 kernel/cgroup/cpuset.c      | 375 ++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 492 insertions(+), 19 deletions(-)

-- 
1.8.3.1