5 ms·
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 mem
by sliken 4y ago
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.
- blip54321 4y agoCores are basically free. 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-vs-Intel-Celeron-N3450/m440vsm208922 https://cpu.userbenchmark.com/Compare/Intel-Pentium-4-300GHz...
- aidenn0 4y agoYou'd be better off comparing to a pentium M. If you put 100 netburst cores on a single die, it would melt [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.
- gruez 4y ago>Pentium IV single-core performance is almost identical to a modern entry-level netbook processor: >https://cpu.userbenchmark.com/Compare/Intel-Pentium-4-300GHz 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.
- Dylan16807 4y ago> Pentium IV single-core performance is almost identical to a modern entry-level netbook processor: https://cpu.userbenchmark.com/Compare/Intel-Pentium-4-300GHz-vs-Intel-Celeron-N3450/m440vsm208922 https://cpu.userbenchmark.com/Compare/Intel-Pentium-4-300GHz... 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.
- UncleEntity 4y agoI’d love to have a computer with a hundred little pentium cores to play around with — makes me wonder why nobody has made one yet (AFAICT). 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?
- NavinF 4y agoYou could get a pair of used epyc 7601 and a motherboard for like $1200. Unlike a hundred little pentium cores, these 64 cores can run real workloads ~4x as fast as a modern desktop in the same price range. 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.
- blip54321 4y agoFor the most part, because you'd be IO-bound, and you'd be limited by single-threaded speed. 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.
- sudosysgen 4y agoMemory throughput keeps increasing. While the number of channels per core doesn't increase, the clock rate keeps increasing, and when it stops increasing then bus width typically increases.
- NavinF 4y ago>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.
- tedunangst 4y agoDDR5 also halved channel width.
- Veliladon 4y agoIronically it makes it faster. TRP and TRCD numbers are getting so big compared to transfer clock rates that it's more efficient to double the bank groups and send data on more smaller channels vs speeding up a single one.
- Dylan16807 4y agoBecause bandwidth has already been increasing exponentially.
- jotm 4y agoDid adding more channels start improving performance in a significant way sometime in the past decade? 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)...
- sliken 4y agoIt's highly workload dependent. Many things are cache friendly and won't care. Adding a integrated GPU definitely shows improvements with increased bandwidth and increased channels. 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.