Messages in this thread | | | Date | Wed, 8 Jan 2014 14:04:07 +0100 | From | Peter Zijlstra <> | Subject | Re: [RFC] sched: CPU topology try |
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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 :-)
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