Hi Mark,
Thanks for your comments.
On 2017/10/17 23:06, Mark Rutland wrote:
> Hi,
>
> Apologies for the delay for this review.
>
> Largely this seems to look OK, but there are a couple of things which
> stick out.
>
> On Tue, Aug 22, 2017 at 04:07:53PM +0800, Shaokun Zhang wrote:
>> +int hisi_uncore_pmu_event_init(struct perf_event *event)
>> +{
>> + struct hw_perf_event *hwc = &event->hw;
>> + struct hisi_pmu *hisi_pmu;
>> +
>> + if (event->attr.type != event->pmu->type)
>> + return -ENOENT;
>> +
>> + /*
>> + * We do not support sampling as the counters are all
>> + * shared by all CPU cores in a CPU die(SCCL). Also we
>> + * do not support attach to a task(per-process mode)
>> + */
>> + if (is_sampling_event(event) || event->attach_state & PERF_ATTACH_TASK)
>> + return -EOPNOTSUPP;
>> +
>> + /* counters do not have these bits */
>> + if (event->attr.exclude_user ||
>> + event->attr.exclude_kernel ||
>> + event->attr.exclude_host ||
>> + event->attr.exclude_guest ||
>> + event->attr.exclude_hv ||
>> + event->attr.exclude_idle)
>> + return -EINVAL;
>> +
>> + /*
>> + * The uncore counters not specific to any CPU, so cannot
>> + * support per-task
>> + */
>> + if (event->cpu < 0)
>> + return -EINVAL;
>> +
>> + /*
>> + * Validate if the events in group does not exceed the
>> + * available counters in hardware.
>> + */
>> + if (!hisi_validate_event_group(event))
>> + return -EINVAL;
>> +
>> + /*
>> + * We don't assign an index until we actually place the event onto
>> + * hardware. Use -1 to signify that we haven't decided where to put it
>> + * yet.
>> + */
>> + hwc->idx = -1;
>> + hwc->config_base = event->attr.config;
>
> Are all event codes valid?
>
No, some event codes are invalid for different PMUs.
> e.g. is it possible that some value passed by the user would cause a
> problem were it written to the hardware?
>
> I see that you only use the low 8 bits of the config field elsewhere, so
> it might make sense to sanity check that here rather than having to mask
> it elsewhere.
Ok, i will add this check for this nice comment.
>
> That would make future extension safer, since no-one could be relying on
> passing a dodgy value in.
>
>> +
>> + hisi_pmu = to_hisi_pmu(event->pmu);
>> + /* Enforce to use the same CPU for all events in this PMU */
>> + event->cpu = hisi_pmu->on_cpu;
>
> I think you need to check hisi_pmu->on_cpu != -1, otherwise we can
> accidentally create a task-bound event if a cluster is offline, and I'm
> not sure how the perf core code would handle here.
>
Ok.
>> +
>> + return 0;
>> +}
>
> [...]
>
>> +int hisi_uncore_pmu_online_cpu(unsigned int cpu, struct hlist_node *node)
>> +{
>> + struct hisi_pmu *hisi_pmu;
>> +
>> + hisi_pmu = hlist_entry_safe(node, struct hisi_pmu, node);
>> +
>> + /*
>> + * If the CPU is associated with the PMU, set it in online_cpus of
>> + * the PMU.
>> + */
>> + if (cpumask_test_cpu(cpu, &hisi_pmu->associated_cpus))
>> + cpumask_set_cpu(cpu, &hisi_pmu->online_cpus);
>> + else
>> + return 0;
>
> This would be a bit nicer as:
>
> if (!cpumask_test_cpu(cpu, &hisi_pmu->associated_cpus))
> return 0;
>
> cpumask_set_cpu(cpu, &hisi_pmu->online_cpus);
>
>
> However, I don't think you need hisi_pmu::online_cpus. That's only used
> for the online/offline callbacks, and you can use the
> hisi_pmu::associated_cpus mask in hisi_uncore_pmu_offline_cpu(), and
> avoid altering any mask here.
>
Ok, shall remove this unnecessary member.
>> +
>> + /* If another CPU is already managing this PMU, simply return. */
>> + if (hisi_pmu->on_cpu != -1)
>> + return 0;
>> +
>> + /* Use this CPU in cpumask for event counting */
>> + hisi_pmu->on_cpu = cpu;
>> +
>> + /* Overflow interrupt also should use the same CPU */
>> + WARN_ON(irq_set_affinity(hisi_pmu->irq, cpumask_of(cpu)));
>> +
>> + return 0;
>> +}
>> +
>> +int hisi_uncore_pmu_offline_cpu(unsigned int cpu, struct hlist_node *node)
>> +{
>> + struct hisi_pmu *hisi_pmu;
>> + cpumask_t pmu_online_cpus;
>> + unsigned int target;
>> +
>> + hisi_pmu = hlist_entry_safe(node, struct hisi_pmu, node);
>> +
>> + /*
>> + * If the CPU is online with the PMU, clear it in online_cpus of
>> + * the PMU.
>> + */
>> + if (!cpumask_test_and_clear_cpu(cpu, &hisi_pmu->online_cpus) ||
>> + (hisi_pmu->on_cpu != cpu))
>> + return 0;
>> +
>> + hisi_pmu->on_cpu = -1;
>> +
>> + /* Any other CPU associated with the PMU is still online */
>> + cpumask_and(&pmu_online_cpus, &hisi_pmu->online_cpus, cpu_online_mask);
>> + target = cpumask_any_but(&pmu_online_cpus, cpu);
>> + if (target >= nr_cpu_ids)
>> + return 0;
>
> I think you can get rid of hisi_pmu::online_cpus, and replace the mask
> manipulation above with:
>
> /* Nothing to do if this CPU doesn't own the PMU */
> if (hisi_pmu->on_cpu != cpu)
> return 0;
>
> /* Give up ownership of the PMU */
> hisi_pmu->on_cpu = -1;
>
> /* Choose a new CPU to migrate ownership of the PMU to */
> cpumask_and(&pmu_online_cpus, &hisi_pmu->associated_cpus,
> cpu_online_mask)
> target = cpumask_any_but(&pmu_online_cpus, cpu);
> if (target >= nr_cpu_ids)
> return 0;
>
Ok.
>> +
>> + perf_pmu_migrate_context(&hisi_pmu->pmu, cpu, target);
>> + /* Use this CPU for event counting */
>> + hisi_pmu->on_cpu = target;
>> + WARN_ON(irq_set_affinity(hisi_pmu->irq, cpumask_of(target)));
>> +
>> + return 0;
>> +}
>> +
>> +/*
>> + * Check whether the CPU is associated with this uncore PMU by SCCL_ID,
>> + * if true, set the associated cpumask of the uncore PMU.
>> + */
>> +void hisi_uncore_pmu_set_cpumask_by_sccl(void *arg)
>
> Perhaps:
>
> hisi_uncore_pmu_check_associate_cpu(struct hisi_pmu *pmu)
>
> It's not clear to me why the arg is a void pointer.
>
>> +{
>> + struct hisi_pmu *hisi_pmu = (struct hisi_pmu *)arg;
>
> This cast shouldn't be necessary.
>
Ok.
>> + u32 sccl_id;
>> +
>> + hisi_read_sccl_and_ccl_id(&sccl_id, NULL);
>> + if (sccl_id == hisi_pmu->sccl_id)
>> + cpumask_set_cpu(smp_processor_id(), &hisi_pmu->associated_cpus);
>> +}
>
> [...]
>
>> +/* Generic pmu struct for different pmu types */
>> +struct hisi_pmu {
>> + struct pmu pmu;
>> + const struct hisi_uncore_ops *ops;
>> + struct hisi_pmu_hwevents pmu_events;
>> + /*
>> + * online_cpus: All online CPUs associated with the PMU
>> + * associated_cpus: All CPUs associated with the PMU who is
>> + * initialised when probe.
>> + */
>> + cpumask_t online_cpus, associated_cpus;
>> + /* CPU used for counting */
>> + int on_cpu;
>> + int irq;
>> + struct device *dev;
>> + struct hlist_node node;
>> + u32 sccl_id;
>> + u32 ccl_id;
>> + /* Hardware information for different pmu types */
>> + void __iomem *base;
>> + /* the ID of the PMU modules */
>> + u32 id;
>
> Is this what hte documentation referred to as the index-id?
>
Yes, shall change as index_id.
Thanks,
Shaokun
> It might make sense to call it index_id.
>
>> + int num_counters;
>> + int counter_bits;
>> +};
>
> Thanks,
> Mark.
>
> .
>
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