Port stackcollapse.py from tools/perf/scripts/python/ to a standalone
script in tools/perf/python/ refactored into a StackCollapseAnalyzer
class.
Improvements compared to the legacy script:
- Traverse sample.callchain directly from perf.session without
allocating per-event dictionaries, and fall back to sample.symbol when
a sample has no callchain.
- Replace deprecated optparse with argparse, adding -i/--input alongside
--include-tid, --include-pid, --no-comm, --tidy-java, and --kernel.
- Handle BrokenPipeError cleanly when output is piped into downstream
tools (such as head or flamegraph.pl).
Add a shell test (test_stackcollapse_python.sh) using a CPU workload
(perf test -w noploop) 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>
