Rasterization & Early-Z: Review Checklist

Review checklist

Review Checklist for Rasterization & Early-Z centers on raster throughput, early-Z kill rate, and overdraw reduction. The objective is to connect profiler evidence to root-cause mechanism and release-safe action.

• Workload scope and target KPI are explicitly documented.

• Profiler + counter evidence is reproducible with revision tags.

• Bottleneck classification is proved with mechanism-level traces.

• Mitigation includes owner, blast radius, and rollback criteria.

• End-to-end benchmark matrix confirms closure.

• Owners signed: raster backend owner, graphics architect, performance engineer.

Signoff ownership

GPU OWNERSHIP LAYERS — Rasterization & Early-Z

artifact area     owner
----------------  ----------------------------
architecture    raster backend owner
RTL/microarch   graphics architect
software/tools  performance engineer

Rule: each metric needs a named owner before signoff.

GPU deep dive

Frame-time stability depends on balancing fixed-function stages with programmable shader pressure.

Concept diagram

GRAPHICS PIPELINE

vertex -> tessellation -> raster -> fragment -> ROP/blend

Metric graph

FRAME-TIME PRESSURE

fragment shading load  ████████
raster backpressure    █████
ROP/blend stalls       ████

Reports and artifacts

• stage occupancy timeline

• early-Z efficiency report

• ROP queue depth

• overdraw heatmap

Mini case study

Async compute overlapped with heavy fragment scenes and triggered ROP queue buildup, causing p99 frame spikes.

Debug branches

• Correlate frame spikes with stage-level queues

• Validate early-Z effectiveness under real content

• Isolate graphics-compute arbitration conflicts

Senior review question

Ask: which metric and benchmark pairing proves this topic is truly closed in production context?

Key takeaways

• Always pair micro-kernel metrics with end-to-end workload impact.

• Lock toolchain, driver, and launch metadata before comparing performance results.

Common pitfalls

• Optimizing occupancy without checking memory-system saturation.

• Comparing profiler captures from different driver or compiler builds.

• Declaring wins without reproducible accuracy and performance gates.

Review checklist explanation

A checklist is not bureaucracy here; it is how GPU teams avoid confusing local wins with product wins. Every signoff item should protect against a known class of false confidence.

For Rasterization & Early-Z, the minimum checklist is workload scope, raster throughput, early-Z kill rate, and overdraw reduction, artifact evidence (raster tile occupancy map, depth-test effectiveness report, and overdraw heatmap), bottleneck classification, owner, rollback path, and full matrix validation.

If the change affects architecture or RTL, include correctness and PPA evidence. If it affects compiler/runtime policy, include compatibility and deployment evidence. If it affects physical design, include timing, IR, thermal, and observability evidence.