> Serving web pages is cheap. You’ll probably hit network I/O limits before you saturate the cores.

It's hard to be network I/O bound when serving web pages. Netflix struggles to be network I/O bound when serving video, which is so much bigger and uses so much less processing.

Epyc started off with 32 cores on PCIe 3, and quickly moved to 64 cores on PCIe 4. When we hit 256 cores it's probably going to have PCIe 6, which means it's still the same I/O per core.

But those numbers are crazy overkill for web serving anyway. If you wanted to allocate about a gigabit per core, with 512 cores across two CPUs, using PCIe 5 to be conservative, you'd need at total of... 16 lanes, for a single 400gb/s card you can buy today.

(This is assuming you mean the I/O from the server to the network. If you're talking about I/O outside the server, then upgrade your switches. Using denser servers doesn't increase your network load, it lets you take the same load and send it to fewer racks. You're already handling the total data somewhere.)

Video being bigger also means it does not fit in lower levels of the cache hierarchy. For a normal website 99% of views should be served entirely from RAM.

I mean, we already run NDR Infiniband, and with sometimes multiple cards per host in our data center, so the numbers are not surprising or out of the this world for me...

Terabit Ethernet also is easy. Just 10 100gbit fibers. Again, not much either in port count, or in physical space needs (port count is ample, fibers are thin).

What I meant is, in a conventional data center, you'll probably hit your allocated bandwidth limits before you saturate a processor like this while serving web pages, unless you're sitting on a big exchange point or the backbone router is not in the next system hall. A single socket Epyc system has 128 PCIe lanes and 12 channel memory. A complete overkill for such a job unless you serve millions, and only have a basement to put your servers with some very fat network pipes.

I'm assuming a situation where you'd need more than one server and there actually are bottlenecks. If one server per datacenter is enough, with no bottlenecks, then great you're done.

If your actually-kept-busy servers get 20x faster and your allocated bandwidth doesn't, there's a point where your racks are almost empty and you have some issues to address with the datacenter owner.

I have written that comment from a datacenter tenant, not as an owner. Of course a proper datacenter providing colo services should have fat pipes to backbone carriers. What I meant is this processor is an overkill just for serving webpages. It makes sense as a virtualization host, or an HPC worker node, software defined storage node or any use case which can flex its muscles. Serving HTML files is not one of them, though.

As for zen3 and zen4, it's been a pleasure to work with good vectorization perf, and it seems they've been doing avx512 'right', at least for HPC I know.

Add to that the 12 channels of DDR per socket and the quite generous cache, and once you've swallowed the need to buy 24 sticks for 2 sockets, these things are beautiful beasts, at what Intel has taught us, a very reasonable price (ask you OEM for prices, public prices on CPUs are nuts).

Lots of water in data centers these days. Works fine. I think the fear about that lost to the utility some years ago.