From mboxrd@z Thu Jan  1 00:00:00 1970
From: Joel Fernandes <joel@joelfernandes.org>
Subject: Re: [PATCH] docs: cgroup-v1: Document the cpuset_v2_mode mount option
Date: Sat, 28 Mar 2020 07:50:26 -0400
Message-ID: <20200328115026.GA135587@google.com>
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To: Waiman Long <longman@redhat.com>
Cc: Tejun Heo <tj@kernel.org>, Li Zefan <lizefan@huawei.com>, Johannes Weiner <hannes@cmpxchg.org>, Jonathan Corbet <corbet@lwn.net>, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-doc@vger.kernel.org, Sonny Rao <sonnyrao@google.com>

On Fri, Mar 27, 2020 at 09:47:48PM -0400, Waiman Long wrote:
> The cpuset in cgroup v1 accepts a special "cpuset_v2_mode" mount
> option that make cpuset.cpus and cpuset.mems behave more like those in
> cgroup v2.  Document it to make other people more aware of this feature
> that can be useful in some circumstances.
> 
> Signed-off-by: Waiman Long <longman@redhat.com>

Acked-by: Joel Fernandes (Google) <joel@joelfernandes.org>

thanks,

 - Joel

> ---
>  Documentation/admin-guide/cgroup-v1/cpusets.rst | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/Documentation/admin-guide/cgroup-v1/cpusets.rst b/Documentation/admin-guide/cgroup-v1/cpusets.rst
> index 86a6ae995d54..7ade3abd342a 100644
> --- a/Documentation/admin-guide/cgroup-v1/cpusets.rst
> +++ b/Documentation/admin-guide/cgroup-v1/cpusets.rst
> @@ -223,6 +223,17 @@ cpu_online_mask using a CPU hotplug notifier, and the mems file
>  automatically tracks the value of node_states[N_MEMORY]--i.e.,
>  nodes with memory--using the cpuset_track_online_nodes() hook.
>  
> +The cpuset.effective_cpus and cpuset.effective_mems files are
> +normally read-only copies of cpuset.cpus and cpuset.mems files
> +respectively.  If the cpuset cgroup filesystem is mounted with the
> +special "cpuset_v2_mode" option, the behavior of these files will become
> +similar to the corresponding files in cpuset v2.  In other words, hotplug
> +events will not change cpuset.cpus and cpuset.mems.  Those events will
> +only affect cpuset.effective_cpus and cpuset.effective_mems which show
> +the actual cpus and memory nodes that are currently used by this cpuset.
> +See Documentation/admin-guide/cgroup-v2.rst for more information about
> +cpuset v2 behavior.
> +
>  
>  1.4 What are exclusive cpusets ?
>  --------------------------------
> -- 
> 2.18.1
>