Ganon (anon.delete@this.gmail.com) on March 25, 2021 5:56 pm wrote:
> My prediction for the immediate future is similar to what is happening today already.
> Not everyone buys the SKUs with the most core count: it would be silly to pay for cores roughly
> beyond what you need to saturate the memory bandwidth in aggregate for your workload.
> DDR5 will allow you to use effectively 2x the core count because it will eventually result in
> ~2x bandwidth (3200 -> 6400 and bandwidth efficiency improvements). Not sure what will happen
> after DDR5 though.
>
> Don't think a L4 is cost-effective, though IBM does have it in their mainframes. You would probably
> better off buying 2+ machines with modest core count and
> DDR5, rather than 1 complex one with L4 cache, HBM, etc.

There is no memory technology called "L4".

L4 just means fourth layer of cache. It can be made with any technology, and if it's on separate die, it can be DRAM, which is very cost-effective.

And Intel has it's SRAM-based LLC working as L4 cache for their iGPUs for ages.