Re: [RFC PATCH 2/5] sched/events: Introduce cfs_rq load tracking trace event

[Dietmar Eggemann]

On 03/28/2017 09:56 AM, Peter Zijlstra wrote:

On Tue, Mar 28, 2017 at 07:35:38AM +0100, Dietmar Eggemann wrote:

[...]

 (1) a root task_group:

     cpu=4 path=/ id=1 load=6 util=331

What's @id and why do we care?

It's a per cgroup/subsystem unique id for every task_group (cpu controller):

struct task_group {
        struct cgroup_subsys_state css {
                ...
                int id;
                ...
        }
        ...
}

The root task group path=/ has id=1 and all autogroups have id=0.

I agree, this id is redundant in case we have the task_group path.