[PATCH v2 2/2] perf jevents: add amd specific device table entry metrics

[Jacob Lefkowitz via B4 Relay <devnull+jlefkowi.akamai.com@kernel.org>]

From: Jacob Lefkowitz <jlefkowi@akamai.com>

Adds AMD specific device table entry metrics to perf jevents.
These metrics are only allowed on Zen 2+ processors and are
implemented using the 'amd_iommu' PMU events.

The list of metrics added are:
- lpm_iommu_dte_miss_rate
- lpm_iommu_dte_lookups

The metrics were tested with the standard 'sleep' workload:

perf stat -M iommudte --per-socket --metric-only -j -a -- sleep 10
{"socket" : "S0", "counters" : 8,
"lookups/s  lpm_iommu_dte_lookups" : "4117.3",
"%  lpm_iommu_dte_miss_rate" : "0.0"}
{"socket" : "S1", "counters" : 0,
"lookups/s  lpm_iommu_dte_lookups" : "none",
"%  lpm_iommu_dte_miss_rate" : "none"}

Signed-off-by: Jacob Lefkowitz <jlefkowi@akamai.com>
---
 tools/perf/pmu-events/amd_metrics.py | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/tools/perf/pmu-events/amd_metrics.py b/tools/perf/pmu-events/amd_metrics.py
index 452b88033492..fd0bd9f16529 100755
--- a/tools/perf/pmu-events/amd_metrics.py
+++ b/tools/perf/pmu-events/amd_metrics.py
@@ -318,6 +318,35 @@ def AmdIotlb() -> Optional[MetricGroup]:
     )
 
 
+def AmdIommudte() -> Optional[MetricGroup]:
+    if _zen_model < 2:
+        return None
+
+    dte_hit = Event("amd_iommu/mem_dte_hit/")
+    dte_mis = Event("amd_iommu/mem_dte_mis/")
+    lookups = dte_hit + dte_mis
+
+    return MetricGroup(
+        "iommudte",
+        [
+            Metric(
+                "lpm_iommu_dte_miss_rate",
+                "IOMMU device table cache miss rate",
+                d_ratio(dte_mis, lookups),
+                "100%"
+            ),
+            Metric(
+                "lpm_iommu_dte_lookups",
+                "IOMMU device table cache lookups",
+                d_ratio(lookups, interval_sec),
+                "lookups/s"
+            )
+        ],
+        description="IOMMU Device Table Cache Metrics"
+    )
+
+
+
 def AmdIommuptw() -> Optional[MetricGroup]:
     if _zen_model < 2:
         return None
@@ -570,6 +599,7 @@ def main() -> None:
         AmdCtxSw(),
         AmdDtlb(),
         AmdIotlb(),
+        AmdIommudte(),
         AmdIommuptw(),
         AmdItlb(),
         AmdLdSt(),

-- 
2.53.0