On 22-Dec 12:46, Peter Zijlstra wrote: > On Fri, Dec 22, 2017 at 11:02:06AM +0000, Patrick Bellasi wrote: > > > @@ -315,8 +315,8 @@ static unsigned int sugov_next_freq_shared(struct > > > sugov_cpu *sg_cpu, u64 time) > > > unsigned long j_util, j_max; > > > s64 delta_ns; > > > > > > - if (j_sg_cpu != sg_cpu) > > > - sugov_get_util(j_sg_cpu); > > > + if (idle_cpu(j)) > > > + continue; > > > > That should work to skip IDLE CPUs... however I'm missing where now we > > get the sugov_get_util(j_sg_cpu) for active CPUs. It has been moved > > somewhere else I guess... > > No, I'm just an idiot... lemme fix that.
Then you just missed a call to sugov_get_util(j_sg_cpu) after the above if... right, actually that was Viresh proposal... > > Moreover, that way don't we completely disregard CFS blocked load for > > IDLE CPUs... as well as DL reserved utilization, which should be > > released only at the 0-lag time? > > I was thinking that since dl is a 'global' scheduler the reservation > would be too and thus the freq just needs a single CPU to be observed; AFAIU global is only the admission control (which is something worth a thread by itself...) while the dl_se->dl_bw are aggregated into the dl_rq->running_bw, which ultimately represents the DL bandwidth required for just a CPU. > but I suppose there's nothing stopping anybody from splitting a clock > domain down the middle scheduling wise. So yes, good point. That makes sense... moreover, using the global utilization, we would end up asking for capacities which cannot be provided by a single CPU. > Blergh that'd make a mess of things again. Actually, looking better at your patch: are we not just ok with that? I mean, we don't need this check on idle_cpu since in sugov_aggregate_util we already skip the util=sg_cpu->max in case of !rq->rt.rt_nr_running, while we aggregate just CFS and DL requests. -- #include <best/regards.h> Patrick Bellasi
