Re: [PATCH V6 09/14] perf/x86/intel: Support TopDown metrics on Ice Lake
From: peterz
Date: Tue Jul 21 2020 - 10:31:22 EST
On Tue, Jul 21, 2020 at 10:23:36AM -0400, Liang, Kan wrote:
> Patch 13 forces the slots event to be part of a metric group. In patch 7,
> for a metric group, we only update the values once with slots event.
> I think the normal case mentioned above should not happen.
>
> + /* Only need to call update_topdown_event() once for group read. */
> + if ((cpuc->txn_flags & PERF_PMU_TXN_READ) &&
> + !is_slots_event(event))
> + return;
> +
> + perf_pmu_disable(event->pmu);
> + x86_pmu.update_topdown_event(event);
> + perf_pmu_enable(event->pmu);
Ah, I missed that.
That also requires SLOTS to be the leader so that it will be the first
read. Did we enforce that somewhere?