The Playstation 4’s CPU frequency is still unknown, despite lots of speculation. Sony have remained tight lipped concerning the machines clock speed, with ‘guesses’ ranging from between 1,6GHZ to 2GHZ. Just a few days ago, I ran with a piece of news discussing the performance of texturing using the “Substance Engine”. Allegorithmic’s middleware engine which helps to produce compressed textures and unique effects.
They released a single benchmark showing the performance in Megabytes per second (MB/s) for various platforms, including the Playstation 4, Xbox One and the PC. The benchmark defied what we thought to be true – that the PS4’s CPU was indeed faster than that of the Xbox One (14MB/s vs 12MB/s). But still was considerably slower than a desktop PC.
Recently, one of the developers behind Project CARS, Andy Tudor ran a short interview with GamingBolt and discussed the performance of the PS4’s CPU.
“It’s been challenging splitting the renderer further across threads in an even more fine-grained manner – even splitting already-small tasks into 2-3ms chunks. The single-core speed is quite slow compared to a high-end PC though so splitting across cores is essential.
“The bottlenecks are mainly in command list building – we now have this split-up of up to four cores in parallel. There are still some bottlenecks to work out with memory flushing to garlic, even after changing to LCUE, the memory copying is still significant.”
The PS4’s CPU is indeed AMD’s Jaguar. The Jaguar is an evolution of AMD’s Bobcat architecture, and both are low powered X86 parts. The PS4’s Jaguar is two modules, each module containing four cores which means there are a total of eight inside the machine. It’s thought that six of the Jaguar’s cores are available for games developers – and this is due to a series of slides that were revealed with the Killzone Shadow Fall Post-Mortem released by Guerrilla games.
As far as I know, LCUE is a driver level shader resource which has one goal – reducing the strain on the consoles CPU. Going wide isn’t a surprise for this generation of consoles, and I’ve long discussed how this is likely going to be a real boon for the PC gamer. Currently a lot of titles simply aren’t optimized for more than three or four cores (threads).
As for the Garlic bus, the developers are speaking about one of the Playstation 4’s buses. The buses are simply a communications path for data to be shunted around the system. In the PS4’s case, there are a total of three buses. The Onion, the Onion+ and finally the Garlic.
For now, we’re going to have to wait and see. Microsoft have stated that they were indeed CPU bound, and that raising the clock frequency of their own AMD Jaguar from 1.6GHZ to 1.75GHZ bought them higher and more stable FPS than raising the GPU clock frequency. For the PS4, it seems that in certain tasks it could also be CPU bound.
It’s likely that the system will need to rely on compute (GPGPU – also known as General Purpose compute on Graphics Processing Unit) to help the CPU with certain tasks. The PS4’s advanced queue system (see here) is certainly going to help. Compute can really help with tasks such as physics and AI.
The Jaguar’s max clock speed in theory is 2GHZ, but it has been considered unlikely that Sony would choose such a high clock speed due to heat, power requirements and yields. We’ll have to just wait until the truth is revealed.