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SubjectRe: [PATCH v8 3/6] cpuset: Add cpuset.sched.load_balance flag to v2
On 17/05/18 16:55, Waiman Long wrote:

[...]

> + 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.

[...]

> + /*
> + * On default hierachy, a load balance flag change is only allowed
> + * in a scheduling domain with no child cpuset.
> + */
> + if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys) && balance_flag_changed &&
> + (!is_sched_domain(cs) || css_has_online_children(&cs->css))) {
> + err = -EINVAL;
> + goto out;
> + }

The rule is actually

- no child cpuset
- and it must be a scheduling domain

Right?

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