Re: [PATCH 7/7] sched: Track sched_entity usage contributions

[bsegall]

Morten Rasmussen <morten.rasmussen@xxxxxxx> writes:

> Adds usage contribution tracking for both task and group entities.
> Maintains a non-priority scaled se->avg.usage_avg_contrib for each
> sched_entity and cfs_rq.usage_util_avg sum of all entity contributions.
> The latter provides a more accurate estimate of the true cpu utilization
> than the existing cfs_rq.runnable_load_avg (+blocked_load_avg).
>
> Unlike se->avg.load_avg_contrib, se->avg.usage_avg_contrib for group
> entities is the sum of se->avg.usage_avg_contrib for all entities on the
> group runqueue. It is _not_ influenced in any way by the task group
> h_load. Hence it is representing the actual cpu usage of the group, not
> its intended load contribution which may differ significantly from the
> usage on lightly utilized systems.
>
> The cpu usage tracking is available as cpu_rq(cpu)->cfs.usage_util_avg.
> No tracking of blocked usage has been implemented.

Isn't cfs_rq->usage_util_avg basically just
se->avg.usage_avg_sum * 1024 / se->avg.runnable_avg_period, where
se->group_cfs_rq == cfs_rq? (and for the rq as a whole, rq->avg)

The fact that usage_util_avg doesn't track blocked usage seems more
likely to be a problem than an advantage, but maybe not?
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/