From mboxrd@z Thu Jan 1 00:00:00 1970 From: Quentin Perret Subject: Re: [PATCH v7 08/14] sched/topology: Disable EAS on inappropriate platforms Date: Thu, 4 Oct 2018 10:10:48 +0100 Message-ID: <20181004091046.7nn2odqrjy7tp5vx@queper01-lin> References: <20180912091309.7551-1-quentin.perret@arm.com> <20180912091309.7551-9-quentin.perret@arm.com> <20181003162719.GB19252@hirez.programming.kicks-ass.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20181003162719.GB19252@hirez.programming.kicks-ass.net> Sender: linux-kernel-owner@vger.kernel.org To: Peter Zijlstra Cc: rjw@rjwysocki.net, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, gregkh@linuxfoundation.org, mingo@redhat.com, dietmar.eggemann@arm.com, morten.rasmussen@arm.com, chris.redpath@arm.com, patrick.bellasi@arm.com, valentin.schneider@arm.com, vincent.guittot@linaro.org, thara.gopinath@linaro.org, viresh.kumar@linaro.org, tkjos@google.com, joel@joelfernandes.org, smuckle@google.com, adharmap@codeaurora.org, skannan@codeaurora.org, pkondeti@codeaurora.org, juri.lelli@redhat.com, edubezval@gmail.com, srinivas.pandruvada@linux.intel.com, currojerez@riseup.net, javi.merino@kernel.org List-Id: linux-pm@vger.kernel.org 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 ... Thanks, Quentin