The improvement is incorporated into the new Agility SDK for DirectX 12 Ultimate game development. Therefore, for ordinary users, it will not cause any additional cost in the form of component updates. However, this will mean a significant reduction in the impact of system RAM in games. Since it reduces the impact on this graphics card.
GPU download heaps in DirectX will reduce RAM requirements
A graphics card can actually access two different memory pools. On the one hand its own memory, the VRAM, and on the other hand via DMA drives and the PCI Express interface to the system RAM. Of course, the two are in completely different directions. Well, the concept of GPU Upload heaps is that those things that have been done in tandem between the CPU and GPU are not done in the memory of the former, but in the memory of the latter.
Now many of you will say it’s the same as the ReBAR or Resizable BAR but with another name, however, it has a little nuance and that’s the reason why games require a lot more RAM on PC than on consoles. And we don’t say that to say it, you just have to see how any game that is a conversion of a game for PS5 or Xbox Series X ends up needing a total amount of RAM, much more than what comes with consoles and they do not offer better visual performance in many cases in its computer version.
RAM layout is different on consoles and PCs
One of the main differences between video game consoles and the PC is the fact that, for reasons of economy, the former uses the same memory pool as graphics and system memory. That is, if we take a PC we will see that we can have DDR4, DDR5 or one of the LPDDR type memories, on the one hand, for system RAM, then the graphics card with GDDR5, GDDR6 or even HBM memory .
On consoles it’s not like that, there is a single memory pool. In other words, on PC, it’s as if the data were people who live in two different neighborhoods with two different post offices. On the other hand, in the consoles they all live in the same district, but with the particularity that there are also two post offices. The fact is that, in order not to compete, the streets are distributed.
And therein lies the problem. On PS5 and Xbox we have 16 GB of physical memory, of which 3 GB is kept by the system and the rest of the memory can be distributed at will, for example we can make a game use 10 GB as VRAM and leave only 3 GB as RAM for the rest. So any graphics card with less than this memory is already going to experience performance issues.
PC memory system limitations
Having two different memory pools instead of just one on PC also means all video memory is initially in system RAM, so our game consumes 16GB on consoles split into 3GB for system, 10GB for graphics and an additional 3 GB for the rest. game would look like this:
- The 3 GB for the system will depend on the installation of Windows that we use. So it can be that amount, higher or lower.
- The 10 GB for VRAM is copied from SSD or HDD to RAM and from RAM to VRAM, so we will have it twice. Occupying space in both memories.
- Finally the 3 GB would be in the system RAM.
Then we have things like shader compilation, which is done on the PC CPU and the output is copied to video memory. This is something that only happens on computers.
This is why GPU download heaps are the solution to the problem
The advantage of download heaps is that those 10 GB of memory we mentioned earlier would not be duplicated in the graphics card video memory and RAM. Which means not only a reduction of the requirements in this aspect, but also the freeing up of at least one of the cores of the processor which will not have to make continuous copies from one memory to another. In reality, DirectStorage is more than a side application of ReBAR, however, its main use is for computing algorithms where CPU and GPU go hand in hand, such as computing physics in games or collision detection.
However, this will not reduce video memory amount issues that graphics cards of a certain brand have due to the fact that they use memory chips with less capacity. A planned obsolescence of which we had already warned you and which, unfortunately, this will not solve.
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