Re: cpusets: document adding/removing cpus to cpuset elaborately

[Li Zefan <lizf@cn.fujitsu.com>]

Nikanth Karthikesan wrote:
> Writing a pid to the file, tasks adds that task to that cgroup/cpuset. But to
> add a cpu/mem to a cpuset, the new list of cpus should be written to the
> cpuset.mems file which would replace the old list of cpus. Make this clearer
> in the documentation.
> 

Though I think '>' already means overwrite so removing/adding cpus should
always writing the full list of CPUs to 'cpus', more documentation to make
cpuset usage clearer is not bad.

Acked-by: Li Zefan <lizf@cn.fujitsu.com>

> Signed-off-by: Nikanth Karthikesan <knikanth@suse.de>
> 
> ---
> 
> diff --git a/Documentation/cgroups/cpusets.txt b/Documentation/cgroups/cpusets.txt
> index f9ca389..1d7e978 100644
> --- a/Documentation/cgroups/cpusets.txt
> +++ b/Documentation/cgroups/cpusets.txt
> @@ -777,6 +777,18 @@ in cpuset directories:
>  # /bin/echo 1-4 > cpus		-> set cpus list to cpus 1,2,3,4
>  # /bin/echo 1,2,3,4 > cpus	-> set cpus list to cpus 1,2,3,4
>  
> +To add a CPU to a cpuset, write the new list of CPUs including the
> +CPU to be added. To add 6 to the above cpuset:
> +
> +# /bin/echo 1-4,6 > cpus	-> set cpus list to cpus 1,2,3,4,6
> +
> +Similarly to remove a CPU from a cpuset, write the new list of CPUs
> +without the CPU to be removed.
> +
> +To remove all the CPUs:
> +
> +# /bin/echo "" > cpus		-> clear cpus list
> +
>  2.3 Setting flags
>  -----------------
>