Messages in this thread | | | Date | Thu, 5 Jul 2018 14:31:43 +0100 | From | Quentin Perret <> | Subject | Re: [PATCHv4 11/12] sched/core: Disable SD_ASYM_CPUCAPACITY for root_domains without asymmetry |
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Hi Morten,
On Wednesday 04 Jul 2018 at 11:17:49 (+0100), Morten Rasmussen wrote: > diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c > index 71330e0e41db..29c186961345 100644 > --- a/kernel/sched/topology.c > +++ b/kernel/sched/topology.c > @@ -1160,6 +1160,26 @@ sd_init(struct sched_domain_topology_level *tl, > sd_id = cpumask_first(sched_domain_span(sd)); > > /* > + * Check if cpu_map eclipses cpu capacity asymmetry. > + */ > + > + if (sd->flags & SD_ASYM_CPUCAPACITY) { > + int i; > + bool disable = true; > + long capacity = arch_scale_cpu_capacity(NULL, sd_id); > + > + for_each_cpu(i, sched_domain_span(sd)) { > + if (capacity != arch_scale_cpu_capacity(NULL, i)) { > + disable = false; > + break; > + } > + } > + > + if (disable) > + sd->flags &= ~SD_ASYM_CPUCAPACITY; > + } > + > + /* > * Convert topological properties into behaviour. > */
If SD_ASYM_CPUCAPACITY means that some CPUs have different arch_scale_cpu_capacity() values, we could also automatically _set_ the flag in sd_init() no ? Why should we let the arch set it and just correct it later ?
I understand the moment at which we know the capacities of CPUs varies from arch to arch, but the arch code could just call rebuild_sched_domain when the capacities of CPUs change and let the scheduler detect things automatically. I mean, even if the arch code sets the flag in its topology level table, it will have to rebuild the sched domains anyway ...
What do you think ?
Thanks, Quentin
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