Gears of War: E-Day Uses Xbox Series S SSD to Gain RAM
Developer The Coalition employed a novel technique using the Xbox Series S's NVMe SSD as supplemental RAM, freeing up about one gigabyte of system memory for Gears of War: E-Day.
Gears of War: E-Day launched last week into early access as a first-party Xbox title available on PC, PS5, and Xbox Series X/S. The Coalition, the game's developer, considers it one of Xbox's main exclusives. A technical analysis has revealed the studio used a memory optimization technique on the Xbox Series S, trading a couple of gigabytes of storage for approximately one gigabyte of usable system RAM.
Technical innovation
The Coalition used the console's NVMe SSD storage as a second tier of RAM. This technique swaps data between the system's RAM and the high-speed SSD based on access patterns. Frequently used data stays in RAM, and anything idle can move to the SSD, as Digital Foundry's report described. The system employs what the developers call 'advanced heuristics' to determine which data to move. The solution was co-developed with Xbox's own Advanced Technology Group. Technical director Kate Raynor discussed the SSD usage with the analysts.
Performance trade-offs
This approach prioritizes keeping data constantly needed for gameplay in the system's RAM. The Coalition focused on offloading information not used in a given frame or over a run of frames. This design aims to avoid slowdowns by ensuring the SSD isn't relied upon for active gameplay data. However, performance can degrade over time if the system is forced to refresh the page file on the SSD too frequently.
Context and implications
The technique is not an entirely new concept, bearing similarity to memory swapping used on Mac devices. It arrives in a context where the current console generation may last longer than initially intended, partly due to ongoing memory constraints. The approach may become more necessary as RAM limits persist, particularly in more affordable hardware like the Xbox Series S.
The Xbox Series S is equipped with 10GB of GDDR6 RAM. For Gears of War: E-Day, The Coalition set the entire story in one city, Kalona. This memory optimization method, pioneered for a major first-party title, could influence future Xbox game development. Future high-profile Xbox games like Grand Theft Auto VI and the new Fable may benefit from similar technology to work within hardware limitations.
