Messages in this thread | | | Date | Wed, 30 Nov 2016 11:51:05 +0100 | From | Jiri Olsa <> | Subject | [RFC] perf/x86/intel/uncore: pmu->type->single_fixed question |
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hi, I'm trying to find out some documentation background for this part of uncore code:
--- static int uncore_pmu_event_init(struct perf_event *event) { ... if (event->attr.config == UNCORE_FIXED_EVENT) { /* no fixed counter */ if (!pmu->type->fixed_ctl) return -EINVAL; /* * if there is only one fixed counter, only the first pmu * can access the fixed counter */ if (pmu->type->single_fixed && pmu->pmu_idx > 0) return -EINVAL; ... ---
that for some uncore types (those with pmu->type->single_fixed) only the first pmu (code_id == 0) will allow to touch the clocktick event
other cores boxes will not allow to open clocktick event, eventhough it's announced via /sys/../events/..
I'm probably missing some HW logic of specific boxes that would explain that, but I can't find it.
thanks for info, jirka
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