metric: Add packet retransmission rate to network performance metrics
This patch use total tcp retransmit skb ftrace event count divided by
total net_dev_xmit ftrace event count as packet retransmission rate.
Test: <trace_processor_shell> --run-metrics android_netperf \
<perfetto_trace>
Test: tools/diff_test_trace_processor.py <trace_processor_shell> \
--trace-filter='netperf_metric'
Change-Id: I5c2e0dd79f647ce19e896a8eca52bbb7767d2e46
Perfetto is a production-grade open-source stack for performance instrumentation and trace analysis. It offers services and libraries and for recording system-level and app-level traces, native + java heap profiling, a library for analyzing traces using SQL and a web-based UI to visualize and explore multi-GB traces.
See https://perfetto.dev/docs or the /docs/ directory for documentation.