perfetto-trace-analysis

Provide the trace file and describe the symptom. The Skill initializes a scratchpad, reviews domain hints, runs high-level trace metrics, then drills into slices and thread states with Perfetto SQL until it isolates the root cause of the jank.

Queries are executed with the trace_processor wrapper using the --query-string flag, for example ./trace_processor --query-string "QUERY" trace_file. The Skill validates each query against the standard library schema documentation before running it.

It covers CPU contention and scheduling latency, graphics jank and GPU memory, I/O stalls and uninterruptible sleep, binder IPC bottlenecks, memory pressure and LMK kills, and power drain from wake locks or network traffic.

Wall time differs from CPU time because a thread may be Runnable, Sleeping, or in Uninterruptible Sleep during a slice. The Skill queries the thread_state table for the slice's exact time window to verify what the thread was actually doing.

Analysis depends on what data sources were enabled during trace collection; missing ftrace events or counters limit visibility. Queries are ephemeral with no persisted state between executions, and incomplete slices at trace boundaries have dur = -1 requiring special handling.