Tommy Lahitte
QA Workflow

Capture Unreal Insights Traces with the Right Arguments

Unreal Insights trace files give you a frame-by-frame breakdown of CPU, GPU, task graph, rendering commands, and more. The right combination of -trace= channels makes the difference between a useful trace and an overwhelming one.

unreal-insightstraceprofilingperformanceswitchboard

When reproducing a performance regression or investigating a frame hitch, capturing a good Unreal Insights trace is the first step. The -trace= channels you choose determine what data is captured.

Basic Trace Capture

bash
-tracefile="C:\Logs\MySession.utrace" -trace="default,concert,messaging,tasks" -statnamedevents

Extended Trace for Rendering Analysis

bash
-statnamedevents -trace=cpu,gpu,frame,log,task -tracefile=D:\logs\session.utrace

Full Rendering Pipeline Trace

bash
-trace=log,cpu,gpu,frame,bookmark,concert,messaging,task,rendercommands,rhicommands,rdg

Channels Reference

  • cpu: CPU thread activity and named scopes
  • gpu: GPU timing per pass
  • frame: frame boundaries and frame time
  • log: log messages correlated to timeline
  • task: Task Graph worker activity
  • rendercommands: high level render command queue
  • rhicommands: low-level RHI command timing
  • rdg: Render Dependency Graph pass execution
  • bookmark: named event markers you add in code
  • concert: Multi-User session events (for nDisplay debugging)

Enabling Trace at Runtime

You can also start/stop a trace from the console without a launch argument:

bash
trace.Enable cpu,gpu,frame,log,task    // Start capturing
trace.Disable                           // Stop capturing
The -statnamedevents flag emits named stat scopes as bookmarks, which makes it much easier to correlate code paths with timeline spikes in Unreal Insights.

Related Tips

Profile Memory Usage by Category with LLM

Unreal's Low Level Memory Tracker (LLM) breaks down live memory consumption by stat group: textures, meshes, audio, RHI, and more. Two commands and a launch flag give you a live memory readout in the viewport.

Build a Real Pre-Release Test Pass

A stable editor session is not a release signal. This Unreal-focused pre-release pass combines packaged builds, smoke automation, performance captures, and log review so regressions show up before players do.

Speed Up Builds with Unreal Build Accelerator (UBA)

UBA distributes compilation tasks across a Horde cluster, dramatically reducing full rebuild times. Enabling it is a single XML config change, no code modifications required.