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
Integer Units, Load and Store
The integer unit schedulers can accept up to six micro-ops per cycle, which feed into the 224-entry reorder buffer (up from 192). The Integer unit technically has seven execution ports, comprised of four ALUs (arithmetic logic units) and three AGUs (address generation units).
The schedulers comprise of four 16-entry ALU queues and one 28-entry AGU queue, although the AGU unit can feed 3 micro-ops per cycle into the register file. The AGU queue has increased in size based on AMD’s simulations of instruction distributions in common software. These queues feed into the 180-entry general purpose register file (up from 168), but also keep track of specific ALU operations to prevent potential halting operations.
The three AGUs feed into the load/store unit that can support two 256-bit reads and one 256-bit write per cycle. Not all the three AGUs are equal, judging by the diagram above: AGU2 can only manage stores, whereas AGU0 and AGU1 can do both loads and stores.
The store queue has increased from 44 to 48 entries, and the TLBs for the data cache have also increased. The key metric here though is the load/store bandwidth, as the core can now support 32 bytes per clock, up from 16.
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fmcjw - Tuesday, June 11, 2019 - link
All good and fine, but I want Zen 2 and 7nm on my laptop. If they aren't announcing it today, products aren't gonna ship by holiday 2019, and most consumers will end up buying 10nm Intel devices. Missed chance.mode_13h - Tuesday, June 11, 2019 - link
Eh, they have perfectly good 12 nm laptop SoCs. 7 nm would've been nice, but it's hard to do everything at once.levizx - Tuesday, June 11, 2019 - link
Nope, those 12nm APUs have worse battery life (than current 8th Gen) and no TB3/USB4 support. I can't think of a reason where I would choose Ryzen 3xxxU over Ice Lakemode_13h - Tuesday, June 11, 2019 - link
Do price & availability count?Xyler94 - Tuesday, June 11, 2019 - link
Misleading remarks. Huawei was able to make a Ryzen APU have better battery life than an 8th gen processor. TB3 and USB4 aren't readily used mainstream yet. Heck USB-C hasn't even caught on yet.Currently laptop makers aren't optimizing AMD's CPU, that's just the fact.
Cooe - Wednesday, June 12, 2019 - link
This is mostly nonsense. Performance AND battery life for Ryzen Mobile 2nd Gen is extremely close to Intel's current 8th & 9th gen 4-core parts. And until Ice Lake is a real thing that you can actually buy, Ryzen still has a major value advantage + far better iGPU performance. Ice Lake also isn't really any faster CPU wise than Whiskey Lake, because despite increasing IPC by +18%, clock-speeds were dropped from 4.8 to 4.1GHz, or about -16%, erasing nearly all those gains.fmcjw - Tuesday, June 11, 2019 - link
Yeah, I get that they still need time to get the GPU down to 7nm, so they pushed it back to focus on the CPU for desktop (where performance per watt matters much less than server or mobile). But the silence is not reassuring, and mobile-wise, Zen is still inferior to Intel, maybe not performance-wise as Huawei demonstrates with its Matebook, but definitely battery-wise because of the more powerful GPU.scineram - Tuesday, June 11, 2019 - link
Nobody is going to buy Shintel vaporware. Or only very few.The_Assimilator - Tuesday, June 11, 2019 - link
Please edit the table on page 1 to combine the rows with identical values into a single row (e.g. the RAM speed). Also edit the 3950X price to have a ? after it as it's not yet confirmed.jfmonty2 - Tuesday, June 11, 2019 - link
The 3950X price is most definitely confirmed; Lisa Su said it loud and clear (and showed it on the slide) in AMD's E3 presentation yesterday: https://www.youtube.com/watch?v=yxPBXNuX6Xs&t=...