Sadly dram memory latency has stayed pretty constant over the last decade. As the cores per memory channel keeps increasing, does make one wonder when more memory channels will be added.
Already happened a few months ago. DDR5 doubled the number of memory channels in a normal desktop from 2 to 4. That’s 2 channels per DIMM.
Of course DDR4 still has lower latency today, but that should change next year.
Today the only way to reduce latency is to overclock your RAM. It’s pretty easy to get a $200 DDR4 kit to perform better than what you’d find in $5000 prebuilt PCs.
Interconnect is expensive.
Seriously. A Pentium IV was 40M transistors. A Ryzen V 2000 has around 5 billion transistors. It could fit 100 Pentium IV cores if desired.
That's not desired -- those transistors are better spent bumping up IPC a little bit -- but we can have a perfectly adequate processor at 1% of a modern CPU.
Pentium IV single-core performance is almost identical to a modern entry-level netbook processor:
https://cpu.userbenchmark.com/Compare/Intel-Pentium-4-300GHz...
[edit] or Maybe a Core-2 as that was 64-bit. E7500 with 3MB of cache was dual-core with 228M transistors, which puts you at 40 cores with 60MB of cache for 5B transistors.
>https://cpu.userbenchmark.com/Compare/Intel-Pentium-4-300GHz...
No it isn't.
1. userbenchmark is a joke in the hardware community. just search for "userbenchmark bias". It's also banned from both /r/intel and /r/amd.
2. even they themselves admit that the "modern entry-level netbook processor" is 59% faster in single-threaded performance. The only making up for it is "Memory Latency", which I doubt can make up for a 59% gap in performance.
Almost identical? The wimpy netbook processor is 59% faster on a single core. Ignore that site's overall speed numbers, they make no sense.
But a fair comparison has to be to a desktop chip. Let's look at an i3-12300. It rates +597% on single core performance; seven times faster.
Or one that doesn’t cost big dollars since the arm server chips seem to be going in this direction.
I mean, 256 x86 cores seems perfectly reasonable, right?
Alternatively an old 4 node server could get you there even cheaper if you don’t care that they are separate computers in one chassis. I got a used C6100 with 24 cores across 8 CPU sockets for $600 6 years ago. You could probably get >100 cores for the same price today.
If threads count, the Xeon Phi 7210 64 core 256 thread would be even better at $125. Still x86
A better architecture is to have the same, but as a co-processor for highly multithreaded tasks. That's basically a GPU. You get a few thousand cores on an NVidia 3060, in an architecture designed for this.
To the other comments in the thread:
- I'm mostly giving big-O / ballpark numbers.
- In terms of power, Pentium IV was 180 nm - 65 nm. A 7 nm process can be much more power-efficient.
Last time I checked, single vs dual channel was like a 5-10% performance difference, mostly useful for integrated graphics (and even then latency was the bigger problem)...
Similarly adding enough cores makes the extra channels helpful as well, for that reason servers often have 4x the memory channels as desktops (8 channels vs 2). Even with 8 channels often the performance scaling for using half the cores vs all the cores is poor, at least for the top spec chips.
AMD seems to have realized this and their next gen will have 24 channels instead of 8.