On 11 July 2014 18:13, Morten Rasmussen <morten.rasmus...@arm.com> wrote:
[snip] > > In this example using rq->avg leads to imbalance whereas unweighted load > would not. Correct me if I missed anything. You just miss to take into account how the imbalance is computed > > Coming back to the previous example. I'm not convinced that inflation of > the unweighted load sum when tasks overlap in time is a bad thing. I > have mentioned this before. The average cpu utilization over the 40ms > period is 50%. However the true compute capacity demand is 200% for the > first 15ms of the period, 100% for the next 5ms and 0% for the remaining > 25ms. The cpu is actually overloaded for 15ms every 40ms. This fact is > factored into the unweighted load whereas rq->avg would give you the > same utilization no matter if the tasks are overlapped or not. Hence > unweighted load would give us an indication that the mix of tasks isn't > optimal even if the cpu has spare cycles. > > If you don't care about overlap and latency, the unweighted sum of task > running time (that Peter has proposed a number of times) is better > metric, IMHO. As long the cpu isn't fully utilized. > > Morten -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
