Messages in this thread | | | Date | Fri, 8 Jan 2021 15:51:58 +0000 | From | Ionela Voinescu <> | Subject | Re: [PATCH V4 3/3] arm64: topology: Make AMUs work with modular cpufreq drivers |
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On Friday 08 Jan 2021 at 16:46:53 (+0530), Viresh Kumar wrote: > The AMU counters won't get used today if the cpufreq driver is built as > a module as the amu core requires everything to be ready by late init. > > Fix that properly by registering for cpufreq policy notifier. Note that > the amu core don't have any cpufreq dependency after the first time > CPUFREQ_CREATE_POLICY notifier is called for all the CPUs. And so we > don't need to do anything on the CPUFREQ_REMOVE_POLICY notifier. And for > the same reason we check if the CPUs are already parsed in the beginning > of amu_fie_setup() and skip if that is true. Alternatively we can shoot > a work from there to unregister the notifier instead, but that seemed > too much instead of this simple check. > > While at it, convert the print message to pr_debug instead of pr_info. > > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> > > --- > arch/arm64/kernel/topology.c | 92 +++++++++++++++++++----------------- > 1 file changed, 48 insertions(+), 44 deletions(-) > > diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c > index 57267d694495..e08a4126453a 100644 > --- a/arch/arm64/kernel/topology.c > +++ b/arch/arm64/kernel/topology.c > @@ -199,69 +199,38 @@ static int freq_inv_set_max_ratio(int cpu, u64 max_rate, u64 ref_rate) > return 0; > } > > -static inline void > -enable_policy_freq_counters(int cpu, cpumask_var_t valid_cpus) > -{ > - struct cpufreq_policy *policy = cpufreq_cpu_get(cpu); > - > - if (!policy) { > - pr_debug("CPU%d: No cpufreq policy found.\n", cpu); > - return; > - } > - > - if (cpumask_subset(policy->related_cpus, valid_cpus)) > - cpumask_or(amu_fie_cpus, policy->related_cpus, > - amu_fie_cpus); > - > - cpufreq_cpu_put(policy); > -} > - > static DEFINE_STATIC_KEY_FALSE(amu_fie_key); > #define amu_freq_invariant() static_branch_unlikely(&amu_fie_key) > > -static int __init init_amu_fie(void) > +static void amu_fie_setup(const struct cpumask *cpus) > { > - cpumask_var_t valid_cpus; > bool invariant; > - int ret = 0; > int cpu; > > - if (!zalloc_cpumask_var(&valid_cpus, GFP_KERNEL)) > - return -ENOMEM; > - > - if (!zalloc_cpumask_var(&amu_fie_cpus, GFP_KERNEL)) { > - ret = -ENOMEM; > - goto free_valid_mask; > - } > + /* We are already set since the last insmod of cpufreq driver */ > + if (unlikely(cpumask_subset(cpus, amu_fie_cpus))) > + return; > > - for_each_present_cpu(cpu) { > + for_each_cpu(cpu, cpus) { > if (!freq_counters_valid(cpu) || > freq_inv_set_max_ratio(cpu, > cpufreq_get_hw_max_freq(cpu) * 1000, > arch_timer_get_rate())) > - continue; > - > - cpumask_set_cpu(cpu, valid_cpus); > - enable_policy_freq_counters(cpu, valid_cpus); > + return; > } > > - /* Overwrite amu_fie_cpus if all CPUs support AMU */ > - if (cpumask_equal(valid_cpus, cpu_present_mask)) > - cpumask_copy(amu_fie_cpus, cpu_present_mask); > - > - if (cpumask_empty(amu_fie_cpus)) > - goto free_valid_mask; > + cpumask_or(amu_fie_cpus, amu_fie_cpus, cpus); > > invariant = topology_scale_freq_invariant(); > > /* We aren't fully invariant yet */ > if (!invariant && !cpumask_equal(amu_fie_cpus, cpu_present_mask)) > - goto free_valid_mask; > + return; > > static_branch_enable(&amu_fie_key); > > - pr_info("CPUs[%*pbl]: counters will be used for FIE.", > - cpumask_pr_args(amu_fie_cpus)); > + pr_debug("CPUs[%*pbl]: counters will be used for FIE.", > + cpumask_pr_args(cpus)); > > /* > * Task scheduler behavior depends on frequency invariance support, > @@ -271,13 +240,48 @@ static int __init init_amu_fie(void) > */ > if (!invariant) > rebuild_sched_domains_energy(); > +} > + > +static int init_amu_fie_callback(struct notifier_block *nb, unsigned long val, > + void *data) > +{ > + struct cpufreq_policy *policy = data; > + > + if (val == CPUFREQ_CREATE_POLICY) > + amu_fie_setup(policy->related_cpus); > + > + /* > + * We don't need to handle CPUFREQ_REMOVE_POLICY event as the AMU > + * counters don't have any dependency on cpufreq driver once we have > + * initialized AMU support and enabled invariance. The AMU counters will > + * keep on working just fine in the absence of the cpufreq driver, and > + * for the CPUs for which there are no counters available, the last set > + * value of freq_scale will remain valid as that is the frequency those > + * CPUs are running at. > + */ > + > + return 0; > +} > + > +static struct notifier_block init_amu_fie_notifier = { > + .notifier_call = init_amu_fie_callback, > +}; > + > +static int __init init_amu_fie(void) > +{ > + int ret; > + > + if (!zalloc_cpumask_var(&amu_fie_cpus, GFP_KERNEL)) > + return -ENOMEM; > > -free_valid_mask: > - free_cpumask_var(valid_cpus); > + ret = cpufreq_register_notifier(&init_amu_fie_notifier, > + CPUFREQ_POLICY_NOTIFIER); > + if (ret) > + free_cpumask_var(amu_fie_cpus); > > return ret; > } > -late_initcall_sync(init_amu_fie); > +core_initcall(init_amu_fie); > > bool arch_freq_counters_available(const struct cpumask *cpus) > { > -- > 2.25.0.rc1.19.g042ed3e048af >
Reviewed-by: Ionela Voinescu <ionela.voinescu@arm.com>
Thanks, Ionela.
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