linux-kernel - [PATCH 2/2] perf vendor events arm64 AmpereOneX: Fix frontend

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Message-ID: <20250313201559.11332-3-ilkka@os.amperecomputing.com>
Date: Thu, 13 Mar 2025 20:15:59 +0000
From: Ilkka Koskinen <ilkka@...amperecomputing.com>
To: Namhyung Kim <namhyung@...nel.org>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	John Garry <john.g.garry@...cle.com>,
	Will Deacon <will@...nel.org>,
	James Clark <james.clark@...aro.org>,
	Mike Leach <mike.leach@...aro.org>,
	Leo Yan <leo.yan@...ux.dev>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	"Liang, Kan" <kan.liang@...ux.intel.com>,
	Mark Rutland <mark.rutland@....com>
Cc: Ilkka Koskinen <ilkka@...amperecomputing.com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-perf-users@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] perf vendor events arm64 AmpereOneX: Fix frontend_bound calculation

frontend_bound metrics was miscalculated due to different scaling in
a couple of metrics it depends on. Change the scaling to match with
AmpereOne.

Fixes: 16438b652b46 ("perf vendor events arm64 AmpereOneX: Add core PMU events and metrics")
Signed-off-by: Ilkka Koskinen <ilkka@...amperecomputing.com>
---
 .../arch/arm64/ampere/ampereonex/metrics.json          | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/tools/perf/pmu-events/arch/arm64/ampere/ampereonex/metrics.json b/tools/perf/pmu-events/arch/arm64/ampere/ampereonex/metrics.json
index c5d1d22bd034..5228f94a793f 100644
--- a/tools/perf/pmu-events/arch/arm64/ampere/ampereonex/metrics.json
+++ b/tools/perf/pmu-events/arch/arm64/ampere/ampereonex/metrics.json
@@ -229,19 +229,19 @@
     },
     {
         "MetricName": "slots_lost_misspeculation_fraction",
-        "MetricExpr": "(OP_SPEC - OP_RETIRED) / (CPU_CYCLES * #slots)",
+        "MetricExpr": "100 * (OP_SPEC - OP_RETIRED) / (CPU_CYCLES * #slots)",
         "BriefDescription": "Fraction of slots lost due to misspeculation",
         "DefaultMetricgroupName": "TopdownL1",
         "MetricGroup": "Default;TopdownL1",
-        "ScaleUnit": "100percent of slots"
+        "ScaleUnit": "1percent of slots"
     },
     {
         "MetricName": "retired_fraction",
-        "MetricExpr": "OP_RETIRED / (CPU_CYCLES * #slots)",
+        "MetricExpr": "100 * OP_RETIRED / (CPU_CYCLES * #slots)",
         "BriefDescription": "Fraction of slots retiring, useful work",
         "DefaultMetricgroupName": "TopdownL1",
         "MetricGroup": "Default;TopdownL1",
-        "ScaleUnit": "100percent of slots"
+        "ScaleUnit": "1percent of slots"
     },
     {
         "MetricName": "backend_core",
@@ -266,7 +266,7 @@
     },
     {
         "MetricName": "frontend_bandwidth",
-        "MetricExpr": "frontend_bound - frontend_latency",
+        "MetricExpr": "frontend_bound - 100 * frontend_latency",
         "BriefDescription": "Fraction of slots the CPU did not dispatch at full bandwidth - able to dispatch partial slots only (1, 2, or 3 uops)",
         "MetricGroup": "TopdownL2",
         "ScaleUnit": "1percent of slots"
-- 
2.47.0