On Fri, Jul 24, 2020 at 03:19:06PM +0200, pet...@infradead.org wrote:
> 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;
> >
FWIW, I pushed out a branch with all these changes in:
git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git perf/metric
Just to get it some build love, if you want it differently, I'm happy to
throw it all out again.
