Re: [PATCH v3] cpuset: Enable cpuset controller in default hierarchy

From: Waiman Long
Date: Wed Oct 25 2017 - 11:50:47 EST

On 10/06/2017 05:10 PM, Waiman Long wrote:
> Given the fact that thread mode had been merged into 4.14, it is now
> time to enable cpuset to be used in the default hierarchy (cgroup v2)
> as it is clearly threaded.
> The cpuset controller had experienced feature creep since its
> introduction more than a decade ago. Besides the core cpus and mems
> control files to limit cpus and memory nodes, there are a bunch of
> additional features that can be controlled from the userspace. Some of
> the features are of doubtful usefulness and may not be actively used.
> After examining the source code of some sample users like systemd,
> libvirt and lxc for their use of those additional features, only
> memory_migrate is used by libvirt.
> This patch enables cpuset controller in the default hierarchy with a
> minimal set of features. Currently, only memory_migrate is supported.
> We can certainly add more features to the default hierarchy if there
> is a real user need for them later on.
> For features that are actually flags which are set internally, they are
> being combined into a single "cpuset.flags" control file. That includes
> the memory_migrate feature which is the only flag that is currently
> supported. When the "cpuset.flags" file is read, it contains either
> "+mem_migrate" (enabled) or "-mem_migrate" (disabled).
> To enable it, use
> # echo +mem_migrate > cpuset.flags
> To disable it, use
> # echo -mem_migrate > cpuset.flags
> Note that the flag name is changed to "mem_migrate" for better naming
> consistency.
> v3:
> - Further trim the additional features down to just memory_migrate.
> - Update Documentation/cgroup-v2.txt.
> Signed-off-by: Waiman Long <longman@xxxxxxxxxx>

Ping! Any comment on this patch?