Arm Announces Neoverse V1, N2 Platforms & CPUs, CMN-700 Mesh: More Performance, More Cores, More Flexibility
by Andrei Frumusanu on April 27, 2021 9:00 AM EST- Posted in
- CPUs
- Arm
- Servers
- Infrastructure
- Neoverse N1
- Neoverse V1
- Neoverse N2
- CMN-700
PPA & ISO Performance Projections
We’ve noted about the microarchitectural changes in the new V1 and N2 processors, as well as their IPC improvements, but it’s important to actually put things into context of the actual performance and power requirements to reach those figures. Arm presented an ISO-process node figures of what we can expect out of the designs:
Starting off, we’re presented with a refresher of where exactly the Neoverse N1 was projected to end up. Back in 2019, the company had noted that an N1 core with 1MB L2 would take roughly 1.4mm² of area, and use up to 1.8W at 3.1GHz (TSMC 7nm node projection).
We’ve generally seen more conservative implementations (Graviton2) and more aggressive implementations (Altra Q) of the N1, but Arm states that their original presilicon projections ended up within 10% of the actual silicon performance figures of the respective products.
Compared to an N1, the V1 is meant to achieve 50% higher IPC, or 1.5x its predecessor while maintaining the same frequency capabilities.
What’s important to note on the slide here is that Arm is stating that power efficiency ranges from 0.7x to 1x that of the N1. Reversing the calculation for power usage increases, we actually end up with a 1.5x to 2.14x increase, which is actually quite significant. Arm also notes that the core is 1.7x larger than the N1, which is also a significant figure.
SiPearl’s Rhea chip was the first publicly known Neoverse V1 design and it features 72 cores on a N6 process node. The V1 core’s vastly increased power consumption means that it’s going to be incredibly hard to achieve similar clock frequencies while remaining in the similar 250W TDP range such as that of a current-gen top-end 80-core Altra chip, so either the core will have higher TDPs, or running at lower frequencies.
Arm also projects further non-ISO process performance figures which we’ll cover just a bit later, but there the company showcases a reference design of the V1 with 96 cores on 5nm at 2.7GHz. This means that whilst the microarchitecture seemingly would have the same frequency capabilities, the much higher power consumption of the core puts a practical limit onto the maximum frequency of any such larger core count designs.
The Neoverse N2 seems a more appropriate design. Only losing out 10% IPC versus the V1, its power consumption is targeted to be only 1.45x higher than that of an N1, meaning efficiency lands in at an almost equal 96%. The area usage here is also only 1.3x that of an N1.
So generally speaking, the N2 seems to be a linear increase in performance over the N1 – both in performance and power. While this is not a regression in efficiency (well a small one at least), it does actually mean that in terms of frequency and end-performance targets, new N2 designs require larger generational process node improvements for actual vendors to be able to actually achieve the larger IPC and performance improvements that the new microarchitectures are promising.
I take note again of situations and workloads on the Ampere Altra where we’ve seen that there’s lots of workloads where the chip operates at below the TDP because the CPUs are underutilised. If an N2 design would be able to raise performance in such workloads, and more heavily throttle itself in higher demanding high utilisation workloads, it would still mean a net positive performance benefit even regardless of process node progresses. It’s a balance and situation that will be interesting to see how it plays out in eventual Neoverse N2 products.
In terms of absolute IPC improvements, Arm also disclosed a more varied set of workloads and what to expect out of the V1 and N2.
For the V1, the IPC improvements are roughly 50% median, with SPEC CPU essentially ending up at this figure. Arm made emphasis that there’s a set of workloads that are able to take advantage of SVE and the increased vector execution width of the V1 microarchitecture to achieve IPC improvements in excess of 100-125%, which is quite impressive.
The N2’s median IPC increase lands at a median of 32%, with SPEC CPU at roughly those marketed 40% figure. The high-end isn’t as high as that of the V1, but still in excess of +50% IPC.
Finally, Arm also posted estimated figures for the components of SPEC CPU 2017, where we see the generational improvements be relatively even across the workloads, with a few exceptions where the V1’s larger characteristics come into play. There’s also workloads such as 541.leela_r where the N2 actually leads the V1, and Arm explained this by the fact that the N2 is actually a newer microarchitecture with further front-end improvements that aren’t found on the V1.
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mode_13h - Thursday, April 29, 2021 - link
Uh...> 2013, they had the A7 (tiny), A15 (small), and A57
> Then ARM made the leap into 64bit processing around 2016.
A57 is a 64-bit core.
> Contrast that to the new x86 competition in AMD
No. Why would we do that? They were competing in totally different markets, at the time. The only partial overlap was embedded Ryzen.
> There hasn't been any upgrades for the "tiny" portfolio, being stuck to ... Cortex A35 CPU
> There has been only a slight refresh to the "small" portfolio, upgrading to the Cortex A55 CPU
The A35 and A55 both launched in 2017.
> they're a joke, and easily surpassable by the competitors.
In terms of what? PPA? Perf/W? Perf/$? Might want to be sure you're comparing apples to apples and not comparing competing "small" core with ARM "tiny".
> There hasn't been any new "large" category for iGPUs from ARM or competitors
Samsung is using RDNA and MediaTek is licensing a Nvidia GPU for its upcoming SoCs.
Might want to do a little more research, before writing another longpost. I agree that A55 could use a refresh, but ARMv9 will force that, anyway. I don't even know where A35 is used, but same story, there.
It's worth noting that ARM has also been active in the microcontroller market, with both 32-bit and 64-bit offerings.
Kangal - Friday, April 30, 2021 - link
Firstly, apologies.I know the A57 is 64bit, but there have been many (most?) implementations of it running in 32bit mode. The A57 was really a "rough draft" for ARM, in moving towards both "medium" sized cores and into 64bit computing. Hence, it feels more at home next to it's A7 and A15 brethren.
The contrast is there, and necessary to show the landscape of the time. The tech industry is a fast-paced one. And if your code/calculations is agnostic, that it can run on any platform, you would consider all options (not that I recommend people go creating agnostic code, compared to specialized or hardware-accelarated code).
The Cortex A35 launched in 2015. It's long due for an upgrade, or replacement. Where this core likes to be in is in small, low-power, and cheap devices. In particular the microcontroller market as you mentioned. ARM hasn't been as active in this field as you think they have, with many of the products being custom designs from the ODMs.
I already mentioned the A55 was a slight refresh for the A53, and that itself is also surpassed. Have a look at Apple's "small" cores. They are Out-of-Order processors, they are slightly faster than an A73, they use slightly less power than an A53. It's mind boggling. Others disagree, and say they're actually faster than A75, and more efficient than A55... but at this scale we're splitting hairs. With that much room for difference, it's not inconceivable (heck it's likely) that an outside competitor like RISC-V will surpass the A55 in terms of Perf/W, Perf/PPA, Perf/$, or a combination of the lot. And remember, the Cortex-A53 is the most popular core out there, where it's getting stamped out on so many different Chinese products.
Samsung isn't using Radeon iGPUs YET, and neither is MediaTek. Besides, we have yet to see them in the wild and find out details if their architecture. These might be licensed from AMD or Nvidia, but they might be "small" iGPUs instead of "large" iGPU designs. I did forget to mention that the Tegra X1, and some Nvidia SBC did actually use their "large" iGPU architecture (ie Maxwell etc).
The gist of my rant is that ARM was a revolutionist early on, basically creating the market. Then they were extremely innovative and competitive, basically dominating the market. Now they are competitive but not as revolutionary nor as competitive/innovative as they used to. With ARMv9 they have a chance to start fresh, and return to status quo, by having a trifecta of products for the computing industry. I was pointing out the gaps in their history and portfolio. They shouldn't just focus on mobile phones, that's boring.
mode_13h - Friday, April 30, 2021 - link
> The Cortex A35 launched in 2015.Okay, the date I saw was wrong. It seems to have been announced in November 2015. The A55 seems to have been announced in May 2017.
> this core likes to be in is in small, low-power, and cheap devices.
> In particular the microcontroller market as you mentioned.
They have actual microcontrollers, though. The A35 is still too power-hungry (and expensive?) for most IoT devices.
> Have a look at Apple's "small" cores.
You focus on performance and efficiency, but what about area? Apple has a narrower focus and different process, cost, & area targets than ARM.
The point we can definitely agree on is that ARM's bottom & middle tier cores should've been refreshed more frequently. But, everyone seems to think that ARM is directly competing with Apple, but it's not. Their objectives meaningfully differ, resulting in ARM probably being driven more towards making smaller cores than Apple.
It's only at the top end of their mobile stacks that you can really say ARM and Apple are in direct competition. However, even on something like the A78, ARM is still put in a position of having to make compromises that Apple isn't.
> ARM was a revolutionist early on, basically creating the market.
> Now they are competitive but not as revolutionary nor as competitive/innovative as they used to.
That's how these things work. A small upstart has a lot of freedom. The bigger a company gets, the more constrained it becomes by its customers, its market, the cost of changing, and the downside risk. I'm still just not totally convinced that entirely explains what we're seeing.
If they can manage to cleave their server cores entirely from their mobile cores, and then really make big cores that are performance-first (instead of scaled up versions of mostly-performance cores, like the X1 and A78 situation), then we might see them start to compete at Apple's level. Basically, to compete they'd have to start by designing the X1 first, and then make the A78 by putting it on a diet.
> They shouldn't just focus on mobile phones, that's boring.
LOL, it's also where most of their revenue still lies. If you were CEO, you wouldn't last a day.
grant3 - Saturday, May 1, 2021 - link
> LOL, it's also where most of their revenue still lies. If you were CEO, you wouldn't last a day.Focusing on the same-ol' same-ol' business is exactly how once-profitable companies fade into irrelevance as technology moves on. Plenty of mediocre CEOs do that.
A great CEO can find the future revenue opportunities and prove it to the company's owners.
mode_13h - Sunday, May 2, 2021 - link
Yeah, but you can't afford to walk away from your bread and butter. Any new growth areas you pursue can't come at the expense of revenues in your core business. If you even threatened to starve your core business, you'd be out of a job before your new ambitions could ever get off the ground.Just look at what happened with Qualcomm, they tried to invest in new areas, but their investors absolutely wouldn't tolerate it. Granted, they're more exposed than ARM would be, either under Soft Bank or Nvidia.
Kangal - Sunday, May 2, 2021 - link
No, grant3 is exactly right.What you said is EXACTLY what Blockbuster said before they went bankrupt. In case you didn't know, the board members passed the opportunity to buy Netflix for $50 Million. The CEO then tried to right that wrong by acquiring another competitor, and shifting their revenue stream. The board fired their CEO, saying that their late-fee revenue was the bread and butter of their business model. Blockbuster was too narrow focused and stuck in the past, that not only did they miss the opportunity of becoming a whole new behemoth, but they sunk their own ship at the same time.
mode_13h - Sunday, May 2, 2021 - link
> What you said is EXACTLY what Blockbuster said before they went bankrupt.If grant3 is saying that Blockbuster should close half its stores while they're still profitable, to divert money into R&D on getting into the (then) almost non-existent streaming market, no company in the world would do that.
Now, it's not like ARM is ignoring other markets, of course. They just can't turn their back on the mobile market, in order to do so.
> Blockbuster was too narrow focused and stuck in the past
The genius of capitalism is that the failure of Blockbuster to transition into a streaming platform didn't keep streaming from happening. Its investors could even get in on the game by shifting their investments into players in the streaming market. If the CEO was such a believer, he could've quit and gone to work for a streaming company or founded his own.
Also, let's not forget that there have already been losers in streaming, and it wasn't clear Netflix would've successfully made the transition from movies-by-mail. Who remembers Google Video? Yahoo even bought some company in the space. And just last year, there was quibbi. I'm sure there are others I'm forgetting.
I think we all want to see ARM succeed outside of mobile. They're been investing a lot, in order to do so. Some in this very thread have been complaining at their lack of focus on their smaller, lower-power cores (currently A35 & A55), which you could see as evidence they've already been making sacrifices to try and compete outside their niche. I don't know if that's accurate, but it's plausible.
If Nvidia's acquisition goes through (as I expect it will), I hope and expect it will provide ARM with the funds to do even more ambitious things.
Spunjji - Friday, April 30, 2021 - link
That's a sound argument for that expectation - it's definitely long since past time for an update.dotjaz - Tuesday, April 27, 2021 - link
Why would you need rumours when we know for a FACT that there will be an A55 successor unless b.L design is abandoned for no good reason. I'll give you a hint, b.L can't have mixed architectures that's why big cores stayed at ARMv8.2a for so long.eastcoast_pete - Tuesday, April 27, 2021 - link
Maybe the shift to ARMv9 will force ARM's hand with giving the LITTLE cores out-of-order designs; however, current bigLITTLE designs already mix big, out-of-order designs with LITTLE in-order cores like the A55. So, bL can and has worked with mixed architectures for quite a while. However, I hope you are correct in that the shift to ARMv9 will force the issue, and we'll finally get out-of-order LITTLE cores also on non-Apple devices