AMD Zen 2 Microarchitecture Analysis: Ryzen 3000 and EPYC Rome
by Dr. Ian Cutress on June 10, 2019 7:22 PM EST- Posted in
- CPUs
- AMD
- Ryzen
- EPYC
- Infinity Fabric
- PCIe 4.0
- Zen 2
- Rome
- Ryzen 3000
- Ryzen 3rd Gen
Building a core like Zen 2 requires more than just building a core. The interplay between the core, the SoC design, and then the platform requires different internal teams to come together to create a level of synergy that working separately lacks. What AMD has done with the chiplet design and Zen 2 shows great promise, not only in taking advantage of smaller process nodes, but also driving one path on the future of compute.
When going down a process node, the main advantages are lower power. That can be taken in a few ways: lower power for operation at the same performance, or more power budget to do more. We see this with core designs over time: as more power budget is opened or different units within the core get more efficient, that extra power is used to drive cores wider, hopefully increasing raw instruction rate. It’s not an easy equation to solve, as there are many trade-offs: one such example in the Zen 2 core is the relationship between the reduced L1 I-cache that has allowed AMD to double the micro-op cache, which overall AMD expects to help with performance and power. Going into the minutae of what might be possible, at least at a high level, is like playing with Lego for these engineers.
All that being said, Zen 2 looks a lot like Zen. It is part of the same family, which means it looks very similar. What AMD has done with the platform, enabling PCIe 4.0, and putting the design in place to rid the server processors of the NUMA-like environment is going to help AMD in the long run. The outlook is good for AMD here, depending on how high it can drive the frequency of the server parts, but Zen 2 plus Rome is going to remove a good number of questions that customers on the fence had about Zen.
Overall AMD has quoted a +15% core performance improvement with Zen 2 over Zen+. With the core changes, at a high level, that certainly looks feasible. Users focused on performance will love the new 16-core Ryzen 9 3950X, while the processor seems nice an efficient at 105W, so it will be interesting so see what happens at lower power. We're also anticipating a very strong Rome launch here over the next few months, especially with features like double FP performance and QoS, and the raw multithreading performance of 64 cores is going to be an interesting disruptor to the market, especially if priced effectively. We’ll be getting the hardware on hand here soon to present our findings when the processors are launched on July 7th.
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Smell This - Sunday, June 16, 2019 - link
AND ...
it might be 12- to 16 IF links or, another substrate ?
Targon - Thursday, June 13, 2019 - link
Epyc and Ryzen CCX units are TSMC, the true CPU cores. The I/O unit is the only part that comes from Global Foundries, and is probably at TSMC just to satisfy the contracts currently in place.YukaKun - Monday, June 10, 2019 - link
"Users focused on performance will love the new 16-core Ryzen 9 3950X, while the processor seems nice an efficient at 65W, so it will be interesting so see what happens at lower power."Shouldn't that be 105W?
And great read as usual.
Cheers!
jjj - Monday, June 10, 2019 - link
The big problem with this platform is that ST perf per dollar gains are from zero to minimal, depending on SKU.They give us around 20% ST gains (IPC+clocks) but at a cost. Would rather have 10-15% gains for free than to pay for 20%. Pretty much all SKUs need a price drop to become exciting, some about 50$, some a bit less and the 16 cores a lot more.
Got to wonder about memory BW with the 16 cores. 2 channels with 8 cores is one thing but at 16 cores, it might become a limiting factor here and there.
Threska - Tuesday, June 11, 2019 - link
That could be said of any processor. "Yeah, drop the price of whatever it is and we'll love you for it." Improvements cost, just like DVD's costed more than VHS.jjj - Tuesday, June 11, 2019 - link
In the semi business the entire point is to offer significantly more perf per dollar every year. That's what Moore's Law was, 2x the perf at same price every 2 years. Now progress is slower but consumers aren't getting anything anymore.And in pretty much all tech driven areas, products become better every year, even cars. When there is no innovation, it means that the market is dysfunctional. AMD certainly does not innovate here, except on the balance sheet. Innovation means that you get better value and that is missing here. TSMC gives them more perf per dollar, they have additional gains from packaging but those gains do not trickle down to us. At the end of the day even Intel tries to offer 10-15% perf per dollar gains every cycle.
AlyxSharkBite - Tuesday, June 11, 2019 - link
That’s not Moore’s Law at all. It stated that the number of transistors would double. Also it’s been dead a whileSandy bridge 4c 1.16b
Coffee lake 4c is 2.1b (can’t compare the 6c or 8c)
And that’s a lot more than 2 years.
mode_13h - Tuesday, June 11, 2019 - link
Yeah, but those two chips occupy different market segments. So, you should compare Sandybridge i7 vs. Coffelake i7.Teutorix - Tuesday, June 11, 2019 - link
The number of transistors in an IC, not the number of transistors per CPU core. This is an important distinction since a CPU core in Moore's day had very little in it besides registers and an ALU. They didn't integrate FPUs until relatively recently.It's about overall transistor density, nothing more. You absolutely can compare an 8c to a 4c chip, because they are both a single IC.
An 8 core coffee lake chip is 20% smaller than a quad core sandy bridge chip. That's double the CPU cores, double the GPU cores, with probably a massive increase in the transistors/core also.
Moore's law had a minor slowdown with intel stuck at 14nm but its not dead.
Wilco1 - Tuesday, June 11, 2019 - link
Moore's Law is actually accelerating. Just not at Intel. See https://en.wikipedia.org/wiki/Transistor_count - the largest chips now have ~20 Billion transistors, and with 7nm and 5nm it looks like we're getting some more doublings soon.