Sony has issued a statement this week regards the available RAM PlayStation 4 developers will be able to access via the “direct” and “flexible” memory systems.
Revealing that only only 4.5GB of the PS4′s 8GB GDDR5 memory pool is guaranteed to game developers, however in real terms an additional 512MB of physical RAM may be available suggests the new information.
To explain a little more about the PlayStation 4 memory differences: Flexible Memory” is memory managed by the PS4 OS on the game’s behalf, and allows games to use some very nice FreeBSD virtual memory functionality. However this memory is 100 per cent the game’s memory, and is never used by the OS, and as it is the game’s memory it should be easy for every developer to use it.
Where as PlayStation 4 “Direct Memory” is memory allocated under the traditional video game model, so the game controls all aspects of its allocation. The Eurogamer website explains a little more about the statement:
“Based on this information, plus the new source coming forward to explain the properties of flexible memory, our take on this right now is that there is 4.5GB of conventional RAM available to developers, along with the OS-controlled flexible memory Sony describes, in addition to that.
We understand that this is a 1GB virtual address space, split into two areas – 512MB of on-chip RAM is used (the physical area) and another 512MB is “paged”, perhaps like a Windows swap file. But to be clear, of the 8GB of GDDR5 on PS4, our contention is that 5GB of it is available to developers.
The good news is that the amount is static and not dictated by OS functions as we stated in our original post, making it a lot easier for developers to work with.“