Messages in this thread | | | Date | Thu, 5 Jan 2023 10:13:21 +0000 | Subject | Re: [PATCH v5 1/6] perf vendor events arm64: Add topdown L1 metrics for neoverse-n2 | From | John Garry <> |
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On 05/01/2023 10:05, Jing Zhang wrote: >> However, for this value of slot, isn't this discoverable from a system register per core? Quoting the sbsa: "The IMPLEMENTATION DEFINED constant SLOTS is discoverable from the system register PMMIR_EL1.SLOTS." Did you consider how this could be used? >> > > This may be a feasible idea. The value of slots comes from the register PMMIR_EL1, which I can read in > /sys/bus/event_source/device/armv8_pmuv3_*/caps/slots. But how do I replace the slots in MetricExpr with the > read slots values? Currently I understand that parameters in metricExpr only support events and constants. >
Maybe during runtime we could create a pseudo metric/event for SLOT. This metric would be created during init, and it always just returns the value which was read from PMMIR_EL1.
I'm not sure how well that would play will trying to resolve metrics when building generated pmu-events.c, but I don't think it's all too difficult to achieve.
Have you actually read this value for the n2 core? Does look correct?
Thanks, John
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