Timeline Overlay

The timeline overlay shows a selected counter’s sparkline directly above the pipeline stages, synchronized with the pipeline view’s scroll and zoom.

Toggle

Press Cmd+Shift+O to toggle the overlay on/off.

When enabled, a 30px strip appears between the pipeline header and the stage content. The pipeline stages shift down to accommodate it.

Display

The overlay shows:

• Min-max envelope bars of the selected counter’s per-cycle deltas
• Data synchronized with the pipeline viewport (same visible cycle range)
• Subtle background distinguishing it from the pipeline header
• Rates recompute automatically at the current zoom level

Use Case

The overlay lets you correlate counter behavior with pipeline events without switching to the Counters tab. For example:

• Watch IPC drop while inspecting a cache miss stall in the pipeline
• See branch misprediction spikes aligned with flush events
• Monitor dispatch queue pressure alongside instruction flow

Counter Selection

The overlay shows the first counter by default. The selected counter can be configured via the overlay_counter state (currently toggled via the action, which cycles the first counter on/off).