linux-kernel - [PATCH v8 16/52] perf jevents: Add idle metric for AMD zen models

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Message-ID: <20251113032040.1994090-17-irogers@google.com>
Date: Wed, 12 Nov 2025 19:20:04 -0800
From: Ian Rogers <irogers@...gle.com>
To: Adrian Hunter <adrian.hunter@...el.com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Benjamin Gray <bgray@...ux.ibm.com>, 
	Caleb Biggers <caleb.biggers@...el.com>, Edward Baker <edward.baker@...el.com>, 
	Ian Rogers <irogers@...gle.com>, Ingo Molnar <mingo@...hat.com>, 
	James Clark <james.clark@...aro.org>, Jing Zhang <renyu.zj@...ux.alibaba.com>, 
	Jiri Olsa <jolsa@...nel.org>, John Garry <john.g.garry@...cle.com>, Leo Yan <leo.yan@....com>, 
	Namhyung Kim <namhyung@...nel.org>, Perry Taylor <perry.taylor@...el.com>, 
	Peter Zijlstra <peterz@...radead.org>, Samantha Alt <samantha.alt@...el.com>, 
	Sandipan Das <sandipan.das@....com>, Thomas Falcon <thomas.falcon@...el.com>, 
	Weilin Wang <weilin.wang@...el.com>, Xu Yang <xu.yang_2@....com>, linux-kernel@...r.kernel.org, 
	linux-perf-users@...r.kernel.org
Subject: [PATCH v8 16/52] perf jevents: Add idle metric for AMD zen models

Compute using the msr PMU the percentage of wallclock cycles where the
CPUs are in a low power state.

Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/pmu-events/amd_metrics.py | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/tools/perf/pmu-events/amd_metrics.py b/tools/perf/pmu-events/amd_metrics.py
index b6cdeb4f09fe..f51a044b8005 100755
--- a/tools/perf/pmu-events/amd_metrics.py
+++ b/tools/perf/pmu-events/amd_metrics.py
@@ -3,8 +3,9 @@
 import argparse
 import math
 import os
-from metric import (d_ratio, has_event, Event, JsonEncodeMetric, JsonEncodeMetricGroupDescriptions,
-                    LoadEvents, Metric, MetricGroup, Select)
+from metric import (d_ratio, has_event, max, Event, JsonEncodeMetric,
+                    JsonEncodeMetricGroupDescriptions, LoadEvents, Metric,
+                    MetricGroup, Select)
 
 # Global command line arguments.
 _args = None
@@ -12,6 +13,16 @@ _args = None
 interval_sec = Event("duration_time")
 
 
+def Idle() -> Metric:
+    cyc = Event("msr/mperf/")
+    tsc = Event("msr/tsc/")
+    low = max(tsc - cyc, 0)
+    return Metric(
+        "lpm_idle",
+        "Percentage of total wallclock cycles where CPUs are in low power state (C1 or deeper sleep state)",
+        d_ratio(low, tsc), "100%")
+
+
 def Rapl() -> MetricGroup:
     """Processor socket power consumption estimate.
 
@@ -57,6 +68,7 @@ def main() -> None:
     LoadEvents(directory)
 
     all_metrics = MetricGroup("", [
+        Idle(),
         Rapl(),
     ])
 
-- 
2.51.2.1041.gc1ab5b90ca-goog