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

[Peter Zijlstra]

On Tue, Mar 28, 2017 at 07:35:38AM +0100, Dietmar Eggemann wrote:
> The trace event keys load and util (utilization) are mapped to:
> 
>  (1) load : cfs_rq->runnable_load_avg
> 
>  (2) util : cfs_rq->avg.util_avg
> 
> To let this trace event work for configurations w/ and w/o group
> scheduling support for cfs (CONFIG_FAIR_GROUP_SCHED) the following
> special handling is necessary for non-existent key=value pairs:
> 
>  path = "(null)" : In case of !CONFIG_FAIR_GROUP_SCHED.
> 
>  id   = -1       : In case of !CONFIG_FAIR_GROUP_SCHED.
> 
> The following list shows examples of the key=value pairs in different
> configurations for:
> 
>  (1) a root task_group:
> 
>      cpu=4 path=/ id=1 load=6 util=331

What's @id and why do we care?