On Tue, Jun 03, 2014 at 03:02:18PM +0100, Vincent Guittot wrote: > On 3 June 2014 15:22, Morten Rasmussen <morten.rasmus...@arm.com> wrote: > > On Fri, May 23, 2014 at 04:52:58PM +0100, Vincent Guittot wrote: > >> power_orig is only changed for system with a SMT sched_domain level in > >> order to > >> reflect the lower capacity of CPUs. Heterogenous system also have to > >> reflect an > >> original capacity that is different from the default value. > >> > >> Create a more generic function arch_scale_cpu_power that can be also used > >> by > >> non SMT platform to set power_orig. > > > > I did a quick test of the patch set with adjusting cpu_power on > > big.LITTLE (ARM TC2) to reflect the different compute capacities of the > > A15s and A7s. I ran the sysbench cpu benchmark with 5 threads with and > > without the patches applied, but with non-default cpu_powers. > > > > I didn't see any difference in the load-balance. Three tasks ended up on > > the two A15s and two tasks ended up on two of the three A7s leaving one > > unused in both cases. > > > > Using default cpu_power I get one task on each of the five cpus (best > > throughput). Unless I messed something up, it seems that setting > > cpu_power doesn't give me the best throughput with these patches > > applied. > > That's normal this patchset is necessary but not enough to solve the > issue you mention. We also need to fix the way the imbalance is > calculated for such situation. I have planned to push that in another > patchset in order to not mix too much thing together
Based on the commit messages I was just lead to believe that this was a self-contained patch set that also addressed issues related to handling heterogeneous systems. Maybe it would be worth mentioning that this set is only part of the solution somewhere? It is a bit unclear to me how these changes, which appear to mainly improve factoring rt and irq time into cpu_power, will solve the cpu_power issues related to heterogeneous systems. Can you share your plans for the follow up patch set? I think it would be better to review the solution as a whole. I absolutely agree that the imbalance calculation needs to fixed, but I don't think the current rq runnable_avg_sum is the right choice for that purpose for the reasons I pointed out the in other thread. 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/
