perf python: Port rw-by-file from Perl to perf module

Replace the legacy Perl script rw-by-file.pl with a standalone Python
script in tools/perf/python/rw-by-file.py using the perf Python module.

Improvements compared to the legacy Perl script:
- Remove the dependency on libperl and Perf::Trace::Util.
- Encapsulate per-file-descriptor read/write byte and call count
  aggregation in an RwByFile class using perf.session and resolve thread
  command names via session.find_thread(pid, sample_tid).
- Add argparse CLI support (-i/--input and target program filter) and
  full type annotations.

Add a shell test
(test_rw_by_file_python.sh) to verify the standalone script.

Assisted-by: Antigravity:gemini-3.1-pro
Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 68 insertions, 0 deletions

diff --git a/tools/perf/tests/shell/test_rw_by_file_python.sh b/tools/perf/tests/shell/test_rw_by_file_python.sh
new file mode 100755
index 000000000000..98218bf8a39e
--- /dev/null
+++ b/tools/perf/tests/shell/test_rw_by_file_python.sh
@@ -0,0 +1,68 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# rw-by-file python test
+
+set -e
+
+shelldir=$(dirname "$0")
+# shellcheck source=lib/setup_python.sh
+. "${shelldir}"/lib/setup_python.sh
+
+if ! "$PYTHON" -c 'import perf' > /dev/null 2>&1; then
+	echo "Skipping test, perf python module not found"
+	exit 2
+fi
+
+script_dir="$(dirname "$0")/../../python"
+script_path="${script_dir}/rw-by-file.py"
+
+if ! perf check feature -q libtraceevent > /dev/null 2>&1; then
+	echo "Skipping test, libtraceevent is disabled"
+	exit 2
+fi
+
+if [ ! -f "$script_path" ]; then
+	echo "Skipping test, rw-by-file.py not found at $script_path"
+	exit 2
+fi
+
+err=0
+cleanup() {
+	rm -f "${temp_data}" "${temp_out}"
+}
+trap 'cleanup' EXIT TERM INT
+temp_data=$(mktemp /tmp/perf.data.XXXXXX)
+temp_out=$(mktemp /tmp/perf.out.XXXXXX)
+
+echo "Testing rw-by-file.py..."
+
+# Create a perf.data file. Try to get tracepoint data.
+if perf list | grep -q "syscalls:sys_enter_read"; then
+	perf record -e syscalls:sys_enter_read,syscalls:sys_enter_write -a -o "${temp_data}" \
+		-- dd if=/dev/urandom of=/dev/null bs=1M count=10 >/dev/null 2>&1 || \
+		{ echo "Skipping test, perf record failed"; exit 2; }
+else
+	echo "Skipping test, no syscalls:sys_enter_read event"
+	exit 2
+fi
+
+if [ ! -s "${temp_data}" ]; then
+	echo "Skipping test, perf record failed to create data"
+	exit 2
+fi
+
+# Check that the script executes - filtering for "dd" since that's what we ran
+if ! "$PYTHON" "$script_path" -i "${temp_data}" "dd" > "${temp_out}"; then
+	echo "rw-by-file.py test failed"
+	err=1
+else
+	if ! grep -E -q "^ *[0-9]+" "${temp_out}"; then
+		echo "Failed to find metric data rows"
+		err=1
+	else
+		echo "rw-by-file test passed."
+	fi
+fi
+rm -f "${temp_out}"
+
+exit $err