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Message-ID: <00bf227a-75ce-c63c-c740-89b8d2b27e1c@oracle.com>
Date: Thu, 5 Jan 2023 10:13:21 +0000
From: John Garry <john.g.garry@...cle.com>
To: Jing Zhang <renyu.zj@...ux.alibaba.com>,
Ian Rogers <irogers@...gle.com>,
Xing Zhengjun <zhengjun.xing@...ux.intel.com>,
Will Deacon <will@...nel.org>,
James Clark <james.clark@....com>,
Mike Leach <mike.leach@...aro.org>,
Leo Yan <leo.yan@...aro.org>
Cc: linux-arm-kernel@...ts.infradead.org,
linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
Andrew Kilroy <andrew.kilroy@....com>,
Shuai Xue <xueshuai@...ux.alibaba.com>,
Zhuo Song <zhuo.song@...ux.alibaba.com>
Subject: Re: [PATCH v5 1/6] perf vendor events arm64: Add topdown L1 metrics
for neoverse-n2
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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