In his post on popular gaming forum Neogaf, The Tomorrow Children developer Dylan Cuthbert talked in detail about the PS4 game’s use of Asynchronous Compute, and offered some simplified clarification on the terminologies used in Q-Games’ GDC tech presentation. He discussed how the GPU sits idle from time to time during shader operations, and how the asynchronous compute pipelines can be used to supply more work to the GPU during such instances.
In a naive implementation, that second shader can’t run until the first finishes. That means towards the end there will be alot of the GPU hardware sitting around idle until the previous shader finishes. The compute pipes give you a way of supplying more work to the GPU that can fill in the gaps left by graphics.
Cuthbert said that the team at Q-Games was able to save roughly 6ms on a 33.333ms frame by using the asynchronous compute pipelines, further adding that the savings went up to 10ms on their stress test level.
On a 33.333 ms frame, we saved roughly 6ms by using the async compute pipes. Thats where the 18% comes from. Those savings went up to 10ms on our stress test level. Really if you’re working on a AMD GCN GPU, I can’t recommend looking into async compute enough!
On the subject of multiplatform development, Cuthbert said that their implementation of asynchronous compute is doable on both the PS4 and Xbox One, even though the latter has fewer compute pipelines. As long as the platform’s architecture conforms to AMD’s Graphics Core Next specifications, asynchronous compute is a viable option that every game developer should look into. According to Cuthbert, it is even possible to incorporate the technology late in the development cycle and still reap its benefits.
Depending on what kind of work you are doing and what dependencies it has, its possible to hack it in later in the dev cycle and still get very good results. But like most things in life, you can often get far better results if you plan for it upfront.
You’d be insane not to use it. Two out of the three major gaming platforms use AMD GCN now, so if you’re targeting Xbox and PS4 (sorry WiiU devs!) you can do similar implementations. Supposedly the Xbox One has 4x fewer compute pipes* than PS4, but I would expect that they are totally exposed** to developers and usable.
The Tomorrow Children is a Playstation 4 exclusive currently in development at Q-Games. Although it is scheduled for release this Summer, no concrete release date is available as of writing.