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SubjectRe: [PATCH v8 3/6] cpuset: Add cpuset.sched.load_balance flag to v2
On Thu, May 17, 2018 at 04:55:42PM -0400, Waiman Long wrote:
> The sched.load_balance flag is needed to enable CPU isolation similar to
> what can be done with the "isolcpus" kernel boot parameter. Its value
> can only be changed in a scheduling domain with no child cpusets. On
> a non-scheduling domain cpuset, the value of sched.load_balance is
> inherited from its parent.
>
> This flag is set by the parent and is not delegatable.
>
> Signed-off-by: Waiman Long <longman@redhat.com>
> ---
> Documentation/cgroup-v2.txt | 24 ++++++++++++++++++++
> kernel/cgroup/cpuset.c | 53 +++++++++++++++++++++++++++++++++++++++++----
> 2 files changed, 73 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/cgroup-v2.txt b/Documentation/cgroup-v2.txt
> index 54d9e22..071b634d 100644
> --- a/Documentation/cgroup-v2.txt
> +++ b/Documentation/cgroup-v2.txt
> @@ -1536,6 +1536,30 @@ Cpuset Interface Files
> CPUs of the parent cgroup. Once it is set, this flag cannot be
> cleared if there are any child cgroups with cpuset enabled.
>
> + A parent cgroup cannot distribute all its CPUs to child
> + scheduling domain cgroups unless its load balancing flag is
> + turned off.
> +
> + cpuset.sched.load_balance
> + A read-write single value file which exists on non-root
> + cpuset-enabled cgroups. It is a binary value flag that accepts
> + either "0" (off) or a non-zero value (on). This flag is set
> + by the parent and is not delegatable.
> +
> + When it is on, tasks within this cpuset will be load-balanced
> + by the kernel scheduler. Tasks will be moved from CPUs with
> + high load to other CPUs within the same cpuset with less load
> + periodically.
> +
> + When it is off, there will be no load balancing among CPUs on
> + this cgroup. Tasks will stay in the CPUs they are running on
> + and will not be moved to other CPUs.
> +
> + The initial value of this flag is "1". This flag is then
> + inherited by child cgroups with cpuset enabled. Its state
> + can only be changed on a scheduling domain cgroup with no
> + cpuset-enabled children.

I'm confused... why exactly do we have both domain and load_balance ?

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