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The SSDs and the new generation. The revolution in the I/O system to adapt them… To…

by ace
The SSDs and the new generation. The revolution in the I/O system to adapt them... To...

The new generation is at the door, and one of the most heard words is SSD. SSD will be one of the tools that will completely change the landscape of video games, and in this article we will address everything that is known about them and the revolution made in I/O systems to put them at their maximum yield.

The evolution of consoles has been relatively linear. More GPU, more CPU, better disk. But few of the developments were revolutions.

As far as the CPU is concerned we can say that this has always evolved in a basically linear way, but already the GPU this had two revolutions in its charge. The first, the most relevant of all, was the transition from 2D to 3D, and the second, the appearance of the GPGPU or its parallel processing capacity.

However there is another component that, himself, has already led to some revolutions in video games, and that is usually ignored. The Storage and Input/Output system.

This system was the basis of revolutions such as cd ROM. A cheap solution that provided a huge storage capacity, and good reading speed, thus eliminated the need of expensive and limited cartridges.

It was also in another revolution, with the appearance of hard drives that allowed to further increase storage capacity, improve read speeds, and above all… the correcting of existing problems in the games.

And with this generation, the storage system, and the I/O will once again be in the spotlight, with a gigantic revolution.

It should be noted that when it comes to consoles, Sony has been much more open about what it has done with its console than Microsoft, so don’t forget the difference in paragraphs dedicated to each.

But continuing the idea from behind, the consoles will follow in the footsteps of the PC and adopt the SSDs, and they will pass it, because the I/O system of the PCs would be too penalizing for the consoles. But we’ll see about that later.

What is certain is that SSDs have brought reading capabilities never before imagined, and this has allowed the flow of data provided to the system to reach new heights. But in the case of consoles, it’s not just about reading or writing speed, but much more than that.

The reality is that the SSD drives introduced on the PC have provided a great evolution in the level of data transfer capability, but despite this evolution, this technology has brought little or nothing to the universes of PC games. The problem is not only that the market is not all equipped in the same way, which would create problems for computers with HDDs, which also has to be served, but also the supply of a huge stream of compressed data that saturates the system for decompression. The alternative is games already uncompressed, but with large hundreds of gigas in size, something that is out of the way.

These situations have now been addressed by both Sony and Microsoft, as their consoles wanted to have that speed, but could not afford to spend all their resources on data transfer.

Mark Cerny was in this field a source of precious information with his video The Road to PS5. What’s more, the appearance of several Sony patents has also helped you understand what was done on your console. But microsoft… the company that talks the most, when it comes to specifications… She’s quiet. The little that is known beyond the officially published appeared in one or another interview, but in addition to knowing that its solution is called “Velocity Architecture”, its characteristics are still very little explained today.

But what has made it possible to realize, even without these data, that there are clear differences between the solutions, are the reactions of some people linked to the industry. The SSD in general is praised by everyone in particular, but the PS5 has been the subject of extreme praise, clearly showing differences over all other solutions.

A comparison to the SSDs itself, only allows you to see that the Microsoft is 1 TB and the Sony has 825 GB. That Microsoft transfers 2.4 GB /s uncompressed, and that Sony transfers 5.5 GB/s.

These speeds are sequential read speeds. And if Microsoft beats the best HDDs at 10 to 20x, the reality is that at full speed the readability of your SSD falls short of what the current top systems of this generation (not compared to those that come here), offer. The PS5 SSD beats all current offers, but when it comes to reading speed it should be passed soon by the new SSDs that will be released.

The difference here is, of course, in the prices, because probably an SSD higher than the PS5 can cost a good fraction of the total cost of the console.

We know that Sony’s SSD has 12 channels connecting to your NAND memory, and that’s what allows you to speed it up. In fact such a high channel count on PCs, only on SSDs for servers and using drivers to use from 12 to 18 channels. What Sony has here is unheard of in a consumer product.

The use of the 12 channels has however a consequence, the strange capacity of 825 GB of the SSD.  Microsoft, despite having a slower SSD, achieves an additional 175 GB gain here by having a standard 1 TB disk.

It should be noted, however, that both brands offer the possibility of expanding these capabilities, with the purchase of external SSDs. A proprietary solution at Microsoft, and a generic solution, but subject to approval, by Sony.

But these discs aren’t just worth these speeds. A console has limited resources, and disk capabilities are one of them. That’s why the data needs to be compressed.

The problem is that if the data flow is already very high for a normal system, further increase the same, and add real-time decompression, it would be a problem for the console hardware.

The reality is that increasing data transfer capacity creates diverse bottlenecks by the high use of system resources, and that would be something consoles would have to overcome.

Part of the solution has undergone dedicated compression/decompression units, which not only increase the readability of SSDs, but also save more precious disk space, all without having any impact on the use of system resources that are dedicated to the processing of video games.

Using an optimized set of decompressor blocks, and compression algorithms, including the introduction of the Microsoft-side BCPack and Sony-sided Kraken, the consoles achieved a maximum output capacity of 6 GB/s and 22 GB/s respectively. As well as sustained average values, the values pointed are respectively 4.8 GB/s and something between 8 and 9 GB/s.

At the compression level, Microsoft announced that its console that uses Zlib+the BCpack compressor for textures would prove more effective than using the Kraken for everything. The Kraken was more powerful than Zlib in standard compression, but the BCpack, which would compress textures that are the largest source of data, would give Microsoft the advantage.

Some back of the envelope figures:
– Kraken: Reduces the size of a complex non-RDO encoded BC7 format texture (say a normal map) by approx. 20-30%.
– BCPack: Approx. 50+% size reduction. Depends on how far MS pushed the tech. Definitely more effective than just Kraken alone.

— Richard Geldreich (@richgel999) March 22, 2020

This would give Microsoft a 20 to 30% advantage in compression.

However, it was recently revealed a BC compression support, equivalent to that of Xbox, for the PS5.

Introducing Oodle Texture, the latest compression product in the Oodle Family! Oodle Texture is a preconditioner for BC1-BC7 texture formats (also known as supercompression)! https://t.co/PLDI0HxXoK

— radgametools (@radgametools) June 16, 2020

This system works with Kraken and will be free to use for all devs, with hardware support including for PS4, since Zlib is also compatible:

And Oodle Texture also works incredibly with other LZ compressors, so platforms with hardware ZLIB or other BCn wrapper formats will work great! We love all consoles at RAD and we expect developers to use Oodle Texture everywhere – it’s that good.

— radgametools (@radgametools) June 16, 2020

The main feature is RD-optimized BC1-7 compression. You use Oodle Texture as your BCn encoder, you get regular BCn data out, the result just happens to compress a lot better if you then hand it to Kraken, Zip, etc. Combines beautifully with hardware LZ decoders.

— Fabian Giesen (@rygorous) June 16, 2020

But wait, there’s more: Sony has been evaluating Oodle Texture closely during dev and there’s good news: they decided to buy a license covering _all_ PS4/5 titles. So for SKUs shipping on PS4/PS5: you already have a license.

— Fabian Giesen (@rygorous) June 16, 2020

For the consoles, you can use it to generate compressed, tiled BCn and then have the HW decoder dump data straight to GPU mem and use it immediately. No further decode steps, no CPU processing at all.

— Fabian Giesen (@rygorous) June 16, 2020

This compression is 100% compatible with the Ps5 Kraken, and as such does not use any CPU, and quoting from the official website: “Oodle Texture improves kraken reduction from 2.5% in standard coding (lambda=0) to 45% (lambda=40) with very little visual degradation. And can see here on the official website , in the fourth texture from the end, that it manages to reduce kraken compression from 16.44% to 69.50%.

It should also be noted that the average of 8 to 9…


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