[PATCH v3 1/6] perf vendor events arm64: Add topdown L1 metrics for neoverse-n2

Jing Zhang
2022-11-24T17:15:09Z

The formula of topdown L1 on neoverse-n2 is from ARM sbsa7.0 platform
design document [0], D37-38.

However, due to the wrong count of stall_slot and stall_slot_frontend on
neoverse-n2, the real stall_slot and real stall_slot_frontend need to
subtract cpu_cycles, so correct the expression of topdown metrics.
Reference from ARM neoverse-n2 errata notice [1], D117.

Since neoverse-n2 does not yet support topdown L2, metricgroups such as
Cache, TLB, Branch, InstructionsMix, and PEutilization will be added to
further analysis of performance bottlenecks in the following patches.
Reference from ARM PMU guide [2][3].

[0] https://documentation-service.arm.com/static/60250c7395978b529036da86?token=
[1] https://documentation-service.arm.com/static/636a66a64e6cf12278ad89cb?token=
[2] https://documentation-service.arm.com/static/628f8fa3dfaf015c2b76eae8?token=
[3] https://documentation-service.arm.com/static/62cfe21e31ea212bb6627393?token=

Signed-off-by: Jing Zhang <renyu.zj@linux.alibaba.com>
---
.../arch/arm64/arm/neoverse-n2/metrics.json | 34 ++++++++++++++++++++++
1 file changed, 34 insertions(+)
create mode 100644 tools/perf/pmu-events/arch/arm64/arm/neoverse-n2/metrics.json

diff --git a/tools/perf/pmu-events/arch/arm64/arm/neoverse-n2/metrics.json b/tools/perf/pmu-events/arch/arm64/arm/neoverse-n2/metrics.json
new file mode 100644
index 0000000..8628140
--- /dev/null
+++ b/tools/perf/pmu-events/arch/arm64/arm/neoverse-n2/metrics.json
@@ -0,0 +1,34 @@
+[
+ {
+ "MetricExpr": "(stall_slot_frontend - cpu_cycles) / (5 * cpu_cycles)",
+ "PublicDescription": "Frontend bound L1 topdown metric",
+ "BriefDescription": "Frontend bound L1 topdown metric",
+ "MetricGroup": "TopdownL1",
+ "MetricName": "frontend_bound",
+ "ScaleUnit": "100%"
+ },
+ {
+ "MetricExpr": "(1 - op_retired / op_spec) * (1 - (stall_slot - cpu_cycles) / (5 * cpu_cycles))",
+ "PublicDescription": "Bad speculation L1 topdown metric",
+ "BriefDescription": "Bad speculation L1 topdown metric",
+ "MetricGroup": "TopdownL1",
+ "MetricName": "bad_speculation",
+ "ScaleUnit": "100%"
+ },
+ {
+ "MetricExpr": "(op_retired / op_spec) * (1 - (stall_slot - cpu_cycles) / (5 * cpu_cycles))",
+ "PublicDescription": "Retiring L1 topdown metric",
+ "BriefDescription": "Retiring L1 topdown metric",
+ "MetricGroup": "TopdownL1",
+ "MetricName": "retiring",
+ "ScaleUnit": "100%"
+ },
+ {
+ "MetricExpr": "stall_slot_backend / (5 * cpu_cycles)",
+ "PublicDescription": "Backend Bound L1 topdown metric",
+ "BriefDescription": "Backend Bound L1 topdown metric",
+ "MetricGroup": "TopdownL1",
+ "MetricName": "backend_bound",
+ "ScaleUnit": "100%"
+ }
+]
--
1.8.3.1