Hacker News Reader

Comment by sakras | Hacker News Reader

The Ice Lake chips being benchmarked against are server chips, while the 7950X Zen 4 chip used is a consumer chip. So while Ice Lake has been out for a while, it’s also several times more expensive. It’s also worth noting that it took Intel several generations of trying AVX512 to get it working well, so AMD doing it first try really is impressive (even if they did cheat by just having AVX512 be double pumped AVX2).

View on HN

Double-pumped is fine: what matters is the new semantics implemented that cannot be expressed efficiently in previous ISAs.

Whether it's comparing latest gen architectures against old architectures or comparing consumer CPUs against enterprise CPUs (or an unholy combination of both), it's all insincere hogwash.

Comparing apples to oranges is not how you determine how good a peach is.

Until the Intel Sapphire Rapids server CPUs will be launched later this month, the Ice Lake/Tiger Lake/Rocket Lake microarchitecture is the best AVX-512 implementation available from Intel, after 15 years since this ISA has been publicly disclosed.

Those differ only in the clock frequency and in a few details that are irrelevant for this particular benchmark.

So the comparison normalized by clock frequency, as done here, is legit, no other better comparison is possible for now.

Even if someone had a Sapphire Rapids sample, they would not be allowed to publish any benchmark yet.

Intel also decided to disable AVX-512 on their consumer CPUs going forward, presumably as long as their P+E core strategy remains in place.

I'm of the understanding AVX-512 is available on Alder Lake and up with an appropriate BIOS and the E cores (if applicable) disabled.

I never looked into it in detail, so I could be mistaken.

Only on older CPUs, they started fusing off AVX512 on newer silicon batches (even on 12th gen)

Is there a source for a decision having been made for _all_ their consumer CPUs, not just ADL?

Reply on news.ycombinator.com