[PATCH v3 4/4] selftests/verification: test per-edge dwell-time statistics

[Tobias Schaffner]

Enable a per-cpu monitor, check that the stats file appears and is
populated under load, and skip cleanly when CONFIG_RV_EDGE_STAT is off.

Signed-off-by: Tobias Schaffner <tobias.schaffner@xxxxxxxxxxx>
---
 tools/testing/selftests/verification/config   |  3 ++
 .../verification/test.d/rv_edge_stats.tc      | 37 +++++++++++++++++++
 2 files changed, 40 insertions(+)
 create mode 100644 tools/testing/selftests/verification/test.d/rv_edge_stats.tc

diff --git a/tools/testing/selftests/verification/config b/tools/testing/selftests/verification/config
index 43072c1c38f4..caf3a96ac8b4 100644
--- a/tools/testing/selftests/verification/config
+++ b/tools/testing/selftests/verification/config
@@ -1 +1,4 @@
 CONFIG_RV=y
+CONFIG_PREEMPT_TRACER=y
+CONFIG_RV_MON_WIP=y
+CONFIG_RV_EDGE_STAT=y
diff --git a/tools/testing/selftests/verification/test.d/rv_edge_stats.tc b/tools/testing/selftests/verification/test.d/rv_edge_stats.tc
new file mode 100644
index 000000000000..c03ed6682b80
--- /dev/null
+++ b/tools/testing/selftests/verification/test.d/rv_edge_stats.tc
@@ -0,0 +1,37 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0-or-later
+# description: Test per-edge dwell-time statistics (stats)
+
+MON=wip
+
+check_requires "$MON:monitor"
+
+# The "stats" file is created on enable; if it is still missing the kernel was
+# built without CONFIG_RV_EDGE_STAT, so skip.
+echo 1 > "monitors/$MON/enable"
+if [ ! -e "monitors/$MON/stats" ]; then
+	echo 0 > "monitors/$MON/enable"
+	echo "CONFIG_RV_EDGE_STAT is not enabled."
+	exit_unsupported
+fi
+
+# The first line is the column header; the body has one line per (cpu, edge).
+head -n1 "monitors/$MON/stats" | grep -q "^# cpu edge label valid count sum_ns max_ns"
+[ "$(grep -cvE '^#' "monitors/$MON/stats")" -gt 0 ]
+
+# Drive some scheduler activity so the automaton records transitions.
+for _ in 1 2 3 4 5 6 7 8 9 10; do
+	(true) &
+	wait
+done
+
+# At least one valid edge must now show a non-zero count. Do not require a
+# non-zero dwell: a coarse local_clock() may legitimately return the same
+# value twice.
+grep -vE '^#' "monitors/$MON/stats" | \
+	awk '$4 == 1 && $5 > 0 && $6 >= $7 { hit = 1 } END { exit !hit }'
+
+# An edge the model does not define must never be taken.
+grep -vE '^#' "monitors/$MON/stats" | awk '$4 == 0 && $5 > 0 { exit 1 }'
+
+echo 0 > "monitors/$MON/enable"
-- 
2.53.0