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Comment by chaosbutters | Hacker News Reader

I'm waiting for 64 core CPU. 32 is nice but still not enough.

I feel your comment is just pointlessly snarky without mentioning for what workloads it's not enough.

Nothing is ever enough but we'll always be limited by the economics of scale and in case you're in the exclusive demographic where this doesn't apply to you than you'd have resources for workarounds to performance limitations without complaining (server grade chips, FPGAs, supercomputers, dedicated ASICs, clusters, etc.).

Then you can buy an EPYC 7702P. It's not like they don't make 64 core CPUs. Or get a dual-socket board and buy two 7702s if 128 cores are more to your liking.

Try running kubernetes dev environment with all the crap your team has hoarded on it, elastic, Prometheus, 5 different database engines and dashboard, etc. Then watch the system chug.

Are you on 48 cores currently?

64 cores ought to be enough for anybody...

Yeah, that's what... 10kb of RAM per core?

Funny story. The Vega64 has 8GB of RAM and 4MB of L2 cache (last-level cache) across 4096 SIMD-cores. That's 1kB of L2 cache and 2MB RAM per core.

It gets worse: although there are 4096 cores, the Vega64 isn't fully loaded until you stick 4-threads-per-core (Or more precisely, 16-wavefronts per Compute Unit (256-SIMD-cores)). That means you will actually need to run 16384 SIMD-threads before the Vega64 is fully utilized.

That's less than 512kB main-RAM per core, and less than 256 bytes of L2 cache per core. Better hope your threads are sharing a lot of memory...

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AMD addresses this problem with NAVI / RDNA: NAVI is fully utilized at 1-thread per core. So you only need 2816 threads on the 5700 XT to fully utilize the system.

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