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takyon writes:

Storage Matters: Why Xbox and Playstation SSDs Usher In A New Era of Gaming

A new generation of gaming consoles is due to hit the market later this year, and the hype cycle for the Xbox Series X and Playstation 5 has been underway for more than a year. Solid technical details (as opposed to mere rumors) have been slower to arrive, and we still know much less about the consoles than we typically know about PC platforms and components during the post-announcement, pre-availability phase. We have some top-line performance numbers and general architectural information from Microsoft and Sony, but not quite a full spec sheet.

[...] Solid State Drives were revolutionary for the PC market, providing immense improvements to overall system responsiveness. Games benefited mostly in the form of faster installation and level load times, but fast storage also helped reduce stalls and stuttering when a game needs to load data on the fly. In recent years, NVMe SSDs have provided speeds that are on paper several times faster than what is possible with SATA SSDs, but for gamers the benefits have been muted at best. Conventional wisdom holds that there are two main causes to suspect for this disappointment: First, almost all games and game engines are still designed to be playable off hard drives because current consoles and many low-end PCs lack SSDs. Game programmers cannot take full advantage of NVMe SSD performance without making their games unplayably slow on hard drives. Second, SATA SSDs are already fast enough to shift the bottleneck elsewhere in the system, often in the form of data decompression. Something aside from the SSD needs to be sped up before games can properly benefit from NVMe performance.

Microsoft and Sony are addressing both of those issues with their upcoming consoles. Game developers will soon be free to assume that users will have fast storage, both on consoles and on PCs. In addition, the new generation of consoles will add extra hardware features to address bottlenecks that would be present if they were merely mid-range gaming PCs equipped with cutting-edge SSDs. However, we're still dealing with powerful hype operations promoting these upcoming devices. Both companies are guilty of exaggerating or oversimplifying in their attempts to extol the new capabilities of their next consoles, especially with regards to the new SSDs. And since these consoles are still closed platforms that aren't even on the market yet, some of the most interesting technical details are still being kept secret.

From page 2, dedicated decompression is a key feature:

The most important specialized hardware feature the consoles will include to complement storage performance is dedicated data decompression hardware. Game assets must be stored on disk in a compressed form to keep storage requirements somewhat reasonable. Games usually rely on multiple compression methods—some lossy compression methods specialized for certain types of data (eg. audio and images), and some lossless general-purpose algorithm, but almost everything goes through at least one compression method that is fairly computationally complex. GPU architectures have long included hardware to handle decoding video streams and support simple but fast lossy texture compression methods like S3TC and its successors, but that leaves a lot of data to be decompressed by the CPU. Desktop CPUs don't have dedicated decompression engines or instructions, though many instructions in the various SIMD extensions are intended to help with tasks like this. Even so, decompressing a stream of data at several GB/s is not trivial, and special-purpose hardware can do it more efficiently while freeing up CPU time for other tasks. The decompression offload hardware in the upcoming consoles is implemented on the main SoC so that it can unpack data after it traverses the PCIe link from the SSD and resides in the main RAM pool shared by the GPU and CPU cores.

[...] The CPU time saved by these decompression units sounds astounding: the equivalent of about 9 Zen 2 CPU cores for the PS5, and about 5 for the Xbox Series X. Keep in mind these are peak numbers that assume the SSD bandwidth is being fully utilized—real games won't be able to keep these SSDs 100% busy, so they wouldn't need quite so much CPU power for decompression.

With the CPU and dedicated decompression capability alone, the PS5 will have up to the equivalent performance of 17 Zen 2 CPU cores (more than the Ryzen 9 3950X). Other capabilities may add the equivalent of another one or two cores. Future desktop CPUs may need to add some of these SoC features to handle faster SSD storage.

Original Submission