Messages in this thread | | | Date | Wed, 6 Nov 2013 11:50:03 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v5 3/4] perf,x86: add Intel RAPL PMU support |
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On Tue, Nov 05, 2013 at 06:01:25PM +0100, Stephane Eranian wrote: > +static DEFINE_SPINLOCK(rapl_hotplug_lock);
> +static void rapl_exit_cpu(int cpu) > +{ > + int i, phys_id = topology_physical_package_id(cpu); > + > + spin_lock(&rapl_hotplug_lock);
> + spin_unlock(&rapl_hotplug_lock); > +} > + > +static void rapl_init_cpu(int cpu) > +{ > + int i, phys_id = topology_physical_package_id(cpu); > + > + spin_lock(&rapl_hotplug_lock);
> + spin_unlock(&rapl_hotplug_lock); > +}
> +static int rapl_cpu_starting(int cpu) > +{ > + struct rapl_pmu *pmu2; > + struct rapl_pmu *pmu1 = per_cpu(rapl_pmu, cpu); > + int i, phys_id = topology_physical_package_id(cpu); > + > + if (pmu1) > + return 0; > + > + spin_lock(&rapl_hotplug_lock);
> + spin_unlock(&rapl_hotplug_lock); > + return 0; > +} > + > +static int rapl_cpu_dying(int cpu) > +{ > + struct rapl_pmu *pmu = per_cpu(rapl_pmu, cpu); > + struct perf_event *event, *tmp; > + > + if (!pmu) > + return 0; > + > + spin_lock(&rapl_hotplug_lock);
> + spin_unlock(&rapl_hotplug_lock); > + return 0; > +} > + > +static int rapl_cpu_notifier(struct notifier_block *self, > + unsigned long action, void *hcpu) > +{ > + unsigned int cpu = (long)hcpu; > + > + /* allocate/free data structure for uncore box */ > + switch (action & ~CPU_TASKS_FROZEN) { > + case CPU_UP_PREPARE: > + rapl_cpu_prepare(cpu); > + break; > + case CPU_STARTING: > + rapl_cpu_starting(cpu); > + break; > + case CPU_UP_CANCELED: > + case CPU_DYING: > + rapl_cpu_dying(cpu); > + break; > + case CPU_ONLINE: > + kfree(per_cpu(rapl_pmu_kfree, cpu)); > + per_cpu(rapl_pmu_kfree, cpu) = NULL; > + break; > + case CPU_DEAD: > + per_cpu(rapl_pmu, cpu) = NULL; > + break; > + default: > + break; > + } > + > + /* select the cpu that collects uncore events */ > + switch (action & ~CPU_TASKS_FROZEN) { > + case CPU_DOWN_FAILED: > + case CPU_STARTING: > + rapl_init_cpu(cpu); > + break; > + case CPU_DOWN_PREPARE: > + rapl_exit_cpu(cpu); > + break; > + default: > + break; > + } > + > + return NOTIFY_OK; > +}
What's the point of that rapl_hotplug_lock? It appears all methods its used from are called from hotplug notifiers and those are fully serialized by cpu_add_remove_lock.
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