On Wed, Jan 08, 2014 at 12:52:28PM +0000, Morten Rasmussen wrote: > If I remember correctly, Alex used the rq runnable_avg_sum (in rq->avg) > for this. It is the most obvious choice, but it takes ages to reach > 100%. > > #define LOAD_AVG_MAX_N 345 > > Worst case it takes 345 ms from the system is becomes fully utilized > after a long period of idle until the rq runnable_avg_sum reaches 100%. > > An unweigthed version of cfs_rq->runnable_load_avg and blocked_load_avg > wouldn't have that delay.
Right.. not sure we want to involve blocked load on the utilization metric, but who knows maybe that does make sense. But yes, we need unweighted runnable_avg. > Also, if we are changing the load balance behavior when all cpus are > fully utilized We already have this tipping point. See all the has_capacity bits. But yes, it'd get more involved I suppose. > we may need to think about cases where the load is > hovering around the saturation threshold. But I don't think that is > important yet. Yah.. I'm going to wait until we have a fail case that can give us some guidance before really pondering this though :-) -- 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/