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.

Reviewed-by: Sandipan Das <sandipan.das@amd.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Benjamin Gray <bgray@linux.ibm.com>
Cc: Caleb Biggers <caleb.biggers@intel.com>
Cc: Edward Baker <edward.baker@intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jing Zhang <renyu.zj@linux.alibaba.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Leo Yan <leo.yan@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Perry Taylor <perry.taylor@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Falcon <thomas.falcon@intel.com>
Cc: Weilin Wang <weilin.wang@intel.com>
Cc: Xu Yang <xu.yang_2@nxp.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

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(),
     ])