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Comment by zrm | Hacker News Reader

> I’m more impressed by Xeon Gold vs EPYC perf.

The hardware used in this benchmark isn't very well chosen. All the systems have a different number of cores (Power 16, AMD 32, Intel 40), and the AMD system has the additional disadvantage over the others of being 1P instead of 2P, which approximately halves the available cooling and correspondingly limits clock speeds. The results aren't very surprising given that.

Making comparisons like this can make sense when one of the competitors doesn't make an equivalent product, but they all do make products with an equivalent number of sockets and cores.

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It depends on what you want to compare. If it's performance at a certain price point, you select systems at that point. You can compare on performance per watt or per volume or more abstract comparisons (ideally unbound by price or size) of performance per core, socket or thread at various load factors.

Then test against 2 EPYC 7451s as well for a fairer comparison.

Also, some tuning for the POWER software would probably be very welcome.

I believe the fair comparison would be performance per dollar - comparing similarly priced components. Same sockets and cores can have wildly different costs.

Comparing like with like can give you a better idea of what's going on even if the prices aren't the same. It's a matter of isolating the architecture from the other factors. If a 40 core 2P Intel system is faster than a 32 core 1P AMD system, you don't know if the difference is architectural or just the extra cores and sockets, so you don't know whether to expect a 48 core 2P AMD system to be faster or slower than the Intel system.

And the tested systems aren't equivalently priced here either.

I still need to see raw performance: single core, multi-core single socket, and multi-socket.

Per dollar of CPU, CPU + power, CPU + motherboard, TCO?

> the AMD system has the additional disadvantage over the others of being 1P instead of 2P, which approximately halves the available cooling and correspondingly limits clock speeds.

This doesn't make sense to me. I'd assume each system to be spec'ed correctly for the TDP of the processors. Each system has it's own HSF and case solution.

Multiprocessor systems do perform as less than 2x of their single processor counterparts, but it nothing to do with thermals in a properly designed system.

I wonder how 1P vs 2P would affect memory bandwidth. The 1P vs 2P difference would probably be deeper than just CPU clock speed.

Also, I wonder if these were Meltdown and Spectre patched.

If you are memory throughput bound, and both processors are working independently (think embarrassingly parallelizable problems) you'd probably benefit from the total throughput change.

Otherwise it's pretty easy to get worse performance due to numa issues

EPYC is already four NUMA nodes per socket though.

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