Orbis GPU – compute, queues and pipelines

A lot of rumors are flooding internet about GPU enhancements in PS4. We will try to give more info about this AMD’s custom graphic card inside PS4.

As we said Liverpool GPU is derived from R10XX family from AMD (Southern Islands). Front end blocks, back end blocks, and the basics of the shader cores remain largely unchanged. But they have added some major new additions (mostly aimed at improving the capabilities and efficiences of compute workloads).

Liverpool has multiple compute rings and pipes that provides fine control over how the system resources are divided amongst all of the application’s GPU workloads. This pipelines can perform simulteneous asynchronous compute.

This diagram exposes the queues and pipelines from PS4 GPU (you can click to enlarge the image).

You can compare the PS4 GPU rings (above) with R10XX retail (below)

PS4 GPU has a total of 2 rings and 64 queues on 10 pipelines

- Graphics (GFX) ring and pipeline

• Same as R10xx
• Graphics and compute
• For game

- High Priority Graphics (HP3D) ring and pipeline

• New for Liverpool
• Same as GFX pipeline except no compute capabilities
• For exclusive use by VShell

- 8 Compute-only pipelines

• Each pipeline has 8 queues of a total of 64
• Replaces the 2 compute-only queues and pipelines on R10XX
• Can be used by both game and VShell (likely assign on a pipeline basis, 1 for VShell, and 7 for game)
• Queues can be allocated by game system or by middleware type
• Allows rendering and compute loads to be processed in parallel
• Liverpool compute-only pipelines do not have Constant Update Engines (presented in R10XX cards)