> As a comparison, an IBM z15 mainframe CPU has 10 cores and 256MB per socket.
Well, that's eDRAM magic, isn't it? Most manufacturers are unable to make eDRAM on a CPU.
> My question is why they chose to have just 32MB for up to 80 cores when AMD can choose to have 32MB per 8-core chiplet.
From my understanding, those ARM chips are largely I/O devices: read from disk -> output to Ethernet.
In contrast, IBM's are known for database backends, which likely benefits from gross amounts of L3 cache. EPYC is general purpose: you might run a database on it, you might run I/O constrained apps on it. So kind of a middle ground.
Didn't Intel push eDRAM magic into various laptop chips around Broadwell?
> those ARM chips are largely I/O devices
Anything Neoverse-N1 is pretty good at general compute and databases. There's definitely a lot of Postgres running on AWS Graviton2 instances already :)
Well, that's eDRAM magic, isn't it? Most manufacturers are unable to make eDRAM on a CPU.
> My question is why they chose to have just 32MB for up to 80 cores when AMD can choose to have 32MB per 8-core chiplet.
From my understanding, those ARM chips are largely I/O devices: read from disk -> output to Ethernet.
In contrast, IBM's are known for database backends, which likely benefits from gross amounts of L3 cache. EPYC is general purpose: you might run a database on it, you might run I/O constrained apps on it. So kind of a middle ground.