SSD, data throughput and hardware accelerated decompression


Microsoft has presented the “Xbox Velocity Architecture” of the Xbox Series X in more detail in a very detailed blog article. “Xbox Velocity Architecture” refers to memory management and the speed of data transfer. With the PlayStation 5, Sony also attaches great importance to this “data spinning aspect” and has the edge in terms of pure data throughput rates in this area.
Internal storage (SSD)

  • PlayStation 5: 825 GB Custom SSD
  • Xbox Series X: 1 TB Custom NVME SSD

I/O Throughput

  • PlayStation 5: 5.5 GB / s (Raw) and 8-9 GB / s (Compressed; with custom hardware decompression block)
  • Xbox Series X: 2.4GB / s (Raw) and 4.8GB / s (Compressed; with custom hardware decompression block)

Jason Ronald, Direct of Program Management for the Xbox Series X, explains: “Modern games require a significant amount of data to create the ever more detailed worlds and universes that gamers immerse themselves in with all their senses. To ensure optimal processor performance, all of this data needs to be loaded from disk space into memory The growing size of dynamic open world environments and lively, stable worlds with increased density and diversity has continuously increased the amount of data required. (…) Although modern game engines are able to stream game content from local hard disk storage to main memory , level designers often still have to implement small spaces to overcome the limitations of a traditional hard drive and I / O pipeline, and these in-game elements are often used to obscure the need to erase previous zone assets from memory while loading new assets for the next zone. This egg Restriction would also massively slow down the development of future, immersive games, which is why it significantly influenced the design and development of the Xbox Velocity Architecture. “

The Xbox Velocity Architecture consists of four main components: a dedicated NVME SSD hard drive, hardware accelerated decompression blocks, the DirectStorage API layer, and sampler feedback streaming (SFS). Microsoft explains the four components in the following sections.

NVMe SSD hard drive
Microsoft: “The foundation of Xbox Velocity Architecture is our bespoke 1 terabyte NVME SSD hard drive that delivers raw I / O throughput [Input/Output-Durchsatz] of 2.4 GB / s delivers – more than 40 times the throughput of Xbox One. Conventional SSDs that are used in many PCs often slow down performance as heat builds up or during drive maintenance. The custom-built NVME SSD of the Xbox Series X is designed for consistent, lasting performance alternating with high performance. (…) The same level of consistent, sustainable performance is also provided by the expandable memory card from Seagate, which guarantees a consistently high-performance gaming experience regardless of the location of the game. “

Hardware accelerated decompression
Microsoft: “Game packs and assets are compressed to minimize download times and memory footprint for each individual game. Thanks to hardware-accelerated support for both the LZ decompressor and the new BCPack algorithm specially developed for texture data, developers on Xbox Series X can achieve massive results Savings with no loss of quality or performance These two technologies, used in parallel, significantly reduce the overall size of a game pack by compressing vast amounts of texture data more efficiently, and assuming a 2: 1 compression ratio, Xbox Series X delivers effective I / O performance 4.8 GB / s for the title, which is about 100 times the I / O performance in current generation consoles. To achieve a similarly high decompression performance in software, more than four Zen 2 CPU cores would be required. “

New DirectStorage API
Microsoft: “The standardized file format of the I / O APIs was developed over 30 years ago and has remained practically unchanged, while storage technology has made significant progress since then. When we analyzed game data access patterns and the latest hardware advances with SSD technology, we knew we had to push the state of the art to give developers more control, so we added a brand new DirectStorage API to the DirectX family, giving developers more granular control over their I / O operations and setting up multiple I’s I / O queues enable prioritization and I / O latency are minimized. Thanks to these APIs, developers can use the full I / O performance of the hardware. This means that loading times or fast trips are significantly reduced and literally fast. “

Sampler Feedback Streaming (SFS)
Microsoft: “The new, innovative Sampler Feedback Streaming (SFS) builds on all the new features of the Xbox Velocity Architecture. Game textures are optimized in various levels of detail and resolutions, so-called mipmaps, and can be used during rendering – depending on how close or far Object is away from the player, and as an object moves closer to the player, the resolution of the texture increases to provide crisp details, but these larger mipmaps consume a lot of memory compared to the lower resolution mips that are used if the object is further away. At the moment, developers have to load an entire mip level into memory – even if they only want to sample a very small part of the overall texture. ”

“With special hardware added to the Xbox One X, we were already able to analyze the graphics processor’s use of texture memory, and we found that the graphics processor often accessed less than a third of the texture data loaded. One single scene often contains thousands of different textures, resulting in a significant loss of effective memory and inefficient I / O bandwidth usage, and with this knowledge we were able to develop new features for the Xbox Series X graphics processor, these new features enable partial areas of a mip level to be loaded into memory when the graphics processor needs them, which means that I / O throughput and memory usage will be 2.5 times more effective on average to a pure hardware performance, so SFS offers a clear multiplier for the available system memory d I / O bandwidth, which means more memory and I / O throughput are available to make games even more immersive. ”

“With massive increases in I / O throughput, hardware accelerated decompression, DirectStorage, and significant increases in efficiency through sampler feedback streaming, the Xbox Velocity Architecture Xbox Series X delivers outstanding performance that goes well beyond hardware specifications. It offers direct, instantaneous Access to more than 100 GB of low-level game data stored on the SSD hard drive when the game needs it, innovations that will bring new gaming experiences and unprecedented depth and immersion to the game (…) The Xbox Velocity Architecture (…) ensures completely new approaches to how developers can take advantage of the Xbox Series X and enables fresh rendering techniques and virtual elimination of loading times. (…) In addition, the Xbox Velocity Architecture enables further innovations at the platform level – for example the quick resume feature that allows you to resume where you paused a game over multiple games “, Jason Ronald continues.


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