Messages in this thread | | | Date | Thu, 4 Oct 2018 11:38:48 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v7 08/14] sched/topology: Disable EAS on inappropriate platforms |
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On Thu, Oct 04, 2018 at 10:10:48AM +0100, Quentin Perret wrote: > On Wednesday 03 Oct 2018 at 18:27:19 (+0200), Peter Zijlstra wrote: > > On Wed, Sep 12, 2018 at 10:13:03AM +0100, Quentin Perret wrote: > > > @@ -288,6 +321,21 @@ static void build_perf_domains(const struct cpumask *cpu_map) > > > goto free; > > > tmp->next = pd; > > > pd = tmp; > > > + > > > + /* > > > + * Count performance domains and capacity states for the > > > + * complexity check. > > > + */ > > > + nr_pd++; > > > + nr_cs += em_pd_nr_cap_states(pd->obj); > > > + } > > > + > > > + /* Bail out if the Energy Model complexity is too high. */ > > > + if (nr_pd * (nr_cs + nr_cpus) > EM_MAX_COMPLEXITY) { > > > + if (sched_debug()) > > > + pr_info("rd %*pbl: EM complexity is too high\n ", > > > + cpumask_pr_args(cpu_map)); > > > + goto free; > > > } > > > > I would make than an unconditional WARN, we do not really expect that to > > trigger, but then it does, we really don't want to hide it. > > OTOH that also means that some people with big asymmetric machines can > get a WARN message every time they boot, and even if they don't want to > use EAS. > > Now, that shouldn't happen any time soon, so it's maybe a good thing if > we get reports when/if people start to hit that one, so why not ...
Right, and if becomes a real problem we can think of a solution (like maybe a DT thingy that says to not use EAS, or a 'better' EAS algorithm).
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