alt Hacker NewsWhat is the difference between unified memory and shared memory?
Shared memory existed since the first CPU with an embedded GPU came to market and you could set in BIOS how much memory goes to what component.
I do have an opinion about how unified memory could be different, but I want a proper explanation.
Replies
Gareth321 • today at 7:09 PM
System RAM has much lower bandwidth and less predictable access. Notably, the transfer from system to GPU is very slow. About 30x slower. LLMs aren’t designed to queue or parallelise operations to account for this. They just become much slower.
Shared memory of the past meant reserving a part of the memory for the GPU, which could then not be used or accessed by the CPU. If the CPU wanted to access something, it had to copy it from the GPU's section of the memory to its own. Unified memory means both just fully share the same memory.