On Thu, Jul 23, 2020 at 10:11:11AM -0700, kan.li...@linux.intel.com wrote:
> @@ -3375,6 +3428,72 @@ static int intel_pmu_hw_config(struct perf_event
> *event)
> if (event->attr.type != PERF_TYPE_RAW)
> return 0;
>
> + /*
> + * Config Topdown slots and metric events
> + *
> + * The slots event on Fixed Counter 3 can support sampling,
> + * which will be handled normally in x86_perf_event_update().
> + *
> + * The metric events don't support sampling.
> + *
> + * For counting, topdown slots and metric events will be
> + * handled specially for event update.
> + * A flag PERF_X86_EVENT_TOPDOWN is applied for the case.
> + */
> + if (x86_pmu.intel_cap.perf_metrics && is_topdown_event(event)) {
> + if (is_metric_event(event)) {
> + struct perf_event *leader = event->group_leader;
> + struct perf_event *sibling;
> +
> + /* The metric events don't support sampling. */
> + if (is_sampling_event(event))
> + return -EINVAL;
> +
> + /* The metric events cannot be a group leader. */
> + if (leader == event)
> + return -EINVAL;
> +
> + /*
> + * The slots event cannot be the leader of a topdown
> + * sample-read group, e.g., {slots, topdown-retiring}:S
> + */
> + if (is_slots_event(leader) && is_sampling_event(leader))
> + return -EINVAL;
This has nothing to do with sample-read; SLOTS cannot be sampling when
coupled with the METRIC stuff because hardware is daft.
And you can have SAMPLE_READ on non-leader events just fine.
> +
> + /*
> + * The slots event must be before the metric events,
> + * because we only update the values of a topdown
> + * group once with the slots event.
> + */
> + if (!is_slots_event(leader)) {
> + for_each_sibling_event(sibling, leader) {
> + if (is_slots_event(sibling))
> + break;
> + if (is_metric_event(sibling))
> + return -EINVAL;
> + }
> + }
Per the SIBLING patch this then wants to be:
if (!is_slots_event(leader))
return -EINVAL;
event->event_caps |= PERF_EV_CAP_SIBLING.
/*
* Only once we have a METRICs sibling to we
* need TopDown magic.
*/
leader->hw.flags |= PERF_X86_EVENT_TOPDOWN;
> + }
> +
> + if (!is_sampling_event(event)) {
> + if (event->attr.config1 != 0)
> + return -EINVAL;
How does this depend on sampling?
> + /*
> + * The TopDown metrics events and slots event don't
> + * support any filters.
> + */
> + if (event->attr.config & X86_ALL_EVENT_FLAGS)
> + return -EINVAL;
That seems independent of sampling too. Even a sampling SLOTS shouldn't
be having any of those afaict.
> +
> + event->hw.flags |= PERF_X86_EVENT_TOPDOWN;
This is confusing too, a !sampling SLOTS event without METRIC siblings
shouldn't have this set, right? So arguably, this should be like above.
> +
> + event->event_caps |= PERF_EV_CAP_COEXIST;
> +
> + if (is_metric_event(event))
> + event->hw.flags &=
> ~PERF_X86_EVENT_RDPMC_ALLOWED;
This too seems like something that should be in the is_metric_event()
branch above.
> + }
> + }
> +
> if (!(event->attr.config & ARCH_PERFMON_EVENTSEL_ANY))
> return 0;
>
