In multi-cluster systems, the PMUs can be different across clusters, and so our logical PMU may not be able to schedule events on all CPUs.
This patch adds a cpumask to encode which CPUs a PMU driver supports controlling events for, and limits the driver to scheduling events on those CPUs. Currently the cpumask is set to match all CPUs. Signed-off-by: Mark Rutland <[email protected]> Reviewed-by: Will Deacon <[email protected]> --- arch/arm/include/asm/pmu.h | 1 + arch/arm/kernel/perf_event.c | 20 ++++++++++++++++++++ arch/arm/kernel/perf_event_cpu.c | 10 +++++++++- 3 files changed, 30 insertions(+), 1 deletion(-) diff --git a/arch/arm/include/asm/pmu.h b/arch/arm/include/asm/pmu.h index 56724b2..4688692 100644 --- a/arch/arm/include/asm/pmu.h +++ b/arch/arm/include/asm/pmu.h @@ -65,6 +65,7 @@ struct pmu_hw_events { struct arm_pmu { struct pmu pmu; cpumask_t active_irqs; + cpumask_t supported_cpus; char *name; irqreturn_t (*handle_irq)(int irq_num, void *dev); void (*enable)(struct perf_event *event); diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c index 5bcd8ac..ebcd123 100644 --- a/arch/arm/kernel/perf_event.c +++ b/arch/arm/kernel/perf_event.c @@ -12,6 +12,7 @@ */ #define pr_fmt(fmt) "hw perfevents: " fmt +#include <linux/cpumask.h> #include <linux/kernel.h> #include <linux/platform_device.h> #include <linux/pm_runtime.h> @@ -21,6 +22,11 @@ #include <asm/pmu.h> #include <asm/stacktrace.h> +static bool cpu_supported(struct arm_pmu *armpmu, int cpu) +{ + return cpumask_test_cpu(cpu, &armpmu->supported_cpus); +} + static int armpmu_map_cache_event(const unsigned (*cache_map) [PERF_COUNT_HW_CACHE_MAX] @@ -221,6 +227,10 @@ armpmu_add(struct perf_event *event, int flags) int idx; int err = 0; + /* An event following a process won't be stopped earlier */ + if (!cpu_supported(armpmu, smp_processor_id())) + return -ENOENT; + perf_pmu_disable(event->pmu); /* If we don't have a space for the counter then finish early. */ @@ -417,6 +427,16 @@ static int armpmu_event_init(struct perf_event *event) int err = 0; atomic_t *active_events = &armpmu->active_events; + /* + * Reject CPU-affine events for CPUs that are of a different class to + * that which this PMU handles. Process-following events (where + * event->cpu == -1) can be migrated between CPUs, and thus we have to + * reject them later (in armpmu_add) if they're scheduled on a + * different class of CPU. + */ + if (event->cpu != -1 && !cpu_supported(armpmu, event->cpu)) + return -ENOENT; + /* does not support taken branch sampling */ if (has_branch_stack(event)) return -EOPNOTSUPP; diff --git a/arch/arm/kernel/perf_event_cpu.c b/arch/arm/kernel/perf_event_cpu.c index ae5be75..c1a9880c 100644 --- a/arch/arm/kernel/perf_event_cpu.c +++ b/arch/arm/kernel/perf_event_cpu.c @@ -168,7 +168,8 @@ static void cpu_pmu_init(struct cpu_pmu *cpu_pmu) /* Ensure the PMU has sane values out of reset. */ if (arm_pmu->reset) - on_each_cpu(arm_pmu->reset, arm_pmu, 1); + on_each_cpu_mask(&arm_pmu->supported_cpus, arm_pmu->reset, + arm_pmu, 1); } /* @@ -180,9 +181,13 @@ static void cpu_pmu_init(struct cpu_pmu *cpu_pmu) static int __cpuinit cpu_pmu_notify(struct notifier_block *b, unsigned long action, void *hcpu) { + int cpu = (long)hcpu; if ((action & ~CPU_TASKS_FROZEN) != CPU_STARTING) return NOTIFY_DONE; + if (!cpumask_test_cpu(cpu, &cpu_pmu->supported_cpus)) + return NOTIFY_DONE; + if (cpu_pmu && cpu_pmu->reset) cpu_pmu->reset(cpu_pmu); else @@ -296,6 +301,9 @@ static int cpu_pmu_device_probe(struct platform_device *pdev) goto out_pmu; } + /* Assume by default that we're on a homogeneous system */ + cpumask_setall(&pmu->armpmu.supported_cpus); + if (node && (of_id = of_match_node(cpu_pmu_of_device_ids, pdev->dev.of_node))) { init_fn = of_id->data; ret = init_fn(&pmu->armpmu); -- 1.8.1.1 _______________________________________________ devicetree-discuss mailing list [email protected] https://lists.ozlabs.org/listinfo/devicetree-discuss
