On Sun, 2014-03-23 at 07:19 +0530, Preeti U Murthy wrote:
We were discussing the impact of this consolidation and we are not too sure if it will yield us good power efficiency. So we would want to experiment with the power aware scheduler to find the "sweet spot" for the number of threads to consolidate to and more importantly if there is one such number at all. Else we would not want to go this way at all. Hence it looks best if this patch is dropped until we validate it. We don't want the code getting in and then out if we find out later there are no benefits to it.
I am sorry that I suggested this patch a bit pre-mature in the experimentation and validation stage. When you release the load balancing patchset for power aware scheduler I shall validate this patch. But until then its best if it does not get merged.
It's quite possible that we never find a correct "sweet spot" for all workloads.
Ideally, the "target" number of used threads per core should be a tunable so that the user / distro can "tune" based on a given workload whether to pack cores and how much to pack them, vs. spreading the workload. Akin to scheduling for performance vs. power in a way (though lower perf usually means higher power due to longer running jobs of course).
In any case, we need to experiment.
Cheers, Ben.