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Ampere switching to in-house CPU designs
- throwaway4good 5y agoBut still using ARM ISA?
- liaukovv 5y agoThat's the question I have as well, but since microarchitecture is in large parts dictated by isa how custom it can really be? On the other hand custom isa would require rolling the entire software stack, which is a complete non-starter. Really weird article and announcement
- mhh__ 5y agoCPU design isn't like software. A microarchitecture is some you design rather than adding features in a software-like manner, there is an enormous scope for design choices within a given ISA. And using a custom uarch is also a statement to your customers, shareholders, competitors etc. that you mean business rather than just going the well-trodden path with ARM cores.
- jholman 5y agoI'm not disagreeing with either of your paragraphs, they're both correct... but the thing to note is that, to some degree, they argue in opposite directions. That's because a consequence of the second paragraph is that it's potentially business-profitable to make a "custom uarch" even if you make no use of the enormous scope for design changes.
- mhh__ 5y agoI'm not sure what you mean.
- jholman 5y agoON THE ONE HAND..... The comment you replied to said "with a given ISA, how custom can the uarch be", implying that it would not be very custom. You replied, in your first paragraph, that on the contrary, it could be pretty custom, with the implication being that it probably would be, because that's the value proposition that Ampere is presumably offering. So your paragraph 1 is suggesting that the sentence "Ampere will now use a custom uarch" is an argument that Ampere's custom arch might well be pretty highly customized. ON THE OTHER HAND.... Your second paragraph points out that simply being custom is a social signal (the signal of being, in your words, "that you mean business rather than just going the well-trodden path"). You argue (and I agree) that this social signal might make you more attractive to some customers. I.e. the signal might increase sales. This implies that it would be reasonable for Ampere to spend a certain amount on a barely-custom custom uarch, purely for sales/marketting reasons, as long as it didn't substantially harm performance. You know, because of the implication. So your paragraph 2 is suggesting that the sentence "Ampere will now use a custom uarch" is NOT an argument that Ampere's custom arch has any particular need to be highly customized.
- quanticle 5y ago>but since microarchitecture is in large parts dictated by ISA Well, Apple uses the ARM ISA for their A and M series chips, and but not ARM's microarchitecture, and their chips have significantly higher IPC than comparable parts from Qualcomm or Samsung. Similarly, Intel and AMD both implement the same x86 ISA, but the performance advantage has swung repeatedly between the two. Microarchitecture might be "in large parts" dictated by the ISA, but there's still enough left over for hardware designers to have a significant influence on the overall performance.
- ajb 5y ago"microarchitecture is in large parts dictated by isa " This is very much not the case. Just consider that, for example, Intel still supports running the same ISA that ran on 8086. The microarchitecture now running those instructions isn't at all like the 8086 microarchitecture. (Its running a bunch of other instructions too, but the points stands) An example in the reverse direction, is that a some MIPS chip teams saw that MIPS was dying, and reused their MIPS microarchitectural designs to build ARM processors. Sure, ISA can be designed assuming some things about microarchitecture, and then it can be inconvenient to change it. But not impossible. And during the transition to ARM64, ARM took the opportunity to remove things that were inconvenient for different microarchitectures (eg, directly accessible PC reg, changes to how condition codes work, etc)
- snvzz 5y ago>but since microarchitecture is in large parts dictated by isa Refer to RISC-V unprivileged spec, chapter one. Not dictating microarchitecture is one of its goals.
- andrewcchen 5y agoYes, custom cores in the sense of what apple does.
- karamanolev 5y agoYes: "the fact that Ampere continues to use the Arm architecture is a further encouragement and win for the Arm ecosystem". Personal take: it would be the end of them if they weren't.
- throwaway4good 5y agoSo much for RISC-V then.
- liaukovv 5y agoMaybe risc-v will take current place of arm with arm taking over x86's segment of the market? Risc-v being open would be a real boon for low cost embedded chips
- mhh__ 5y agoThe only companies I can think of that could really make it would probably be Apple (because they have an iron grip over that platform) or Intel (because they actually have good software unlike almost all of their competitors, which could make the migration easier) - Apple are happy with ARM and Intel are probably terrified after what happened with Itanium. Any move to RISC-V will probably either happen in China or incrementally.
- e3bc54b2 5y agoI once read on HN that Apple gets ARM ISA and designs for free by virtue of being a founder. So the closed proprietary nature isn't enough for them to move to RISC V. I'm not sure that's true though..
- philistine 5y agoThey probably have a very generous, very old contract by virtue of being the first third-party to use ARM in a device. But we won't know the specifics unless there's a court case that touches that relationship. With the way Apple operates, we have ten years before we can reasonably assume that they would change their architecture. Is RISC-V really going to be worth all the headaches of a transition in ten years?
- robert_foss 5y agoAmpere probably has an Arm architecture license, which grants them the ability to change Arm designs and use their ISA.
- varispeed 5y agoISA is like API. I don't think you can copyright that, so it would make sense if they did it this way.
- mhh__ 5y agoYes you can. I don't think you can patent trivial details of "API" but you can absolutely patent a given function of an ISA. You probably shouldn't be able to (Alpha vs. MIPS, x86 etc.) but currently you can.
- alkonaut 5y agoWhat does their predictable performance bullet point with "128 cores at consistent frequency" mean? That 128 cores would run at the same frequency?
- viraptor 5y agoSomething related to being able to go full speed without thermal throttling / instruction side effects? I.e. You know what the consistent performance ceiling is, and it won't drop just because you started using avx512 instructions on a nearby core?
- alkonaut 5y agoNot having some instructions be a noisy neighbor is a good idea. But it seems wasteful to cap 128 cores at the power output possible if all cores have that output (if that's what it is). Assuming the default mode of operation is having just a few cores operating at 100% with the majority running at 0%, it's wasteful to not let those active cores run as fast as possible.
- jholman 5y agoWhy would the default mode of operation for a 128-core datacenter chip be to have 120 idle cores? Obviously the default mode of operation is to run all cores, or very nearly all cores, at full tilt all of the time. This chip is designed to be garbage at few-threaded workloads.
- em500 5y agoIndeed. For cloud vendors, a large part of the business model is to resell/oversell idle CPU time as much as they can ("vCPU"), taking advantage of the fact that small/individual clients are usually extremely over-provisioned CPU-wise.
- alkonaut 5y agoThat depends on the workload? For HPC it’s easy, for other loads like DBs or VMs it’s harder, especially with fewer nodes (e.g a single node running 32 VMs with dedicated cores will probably look a lot like a desktop workload with lots of idle cores). I suppose it’s going to be rare to see these in deployments with fewer than several dozen sockets, and workloads must be balanced (so e.g not using dedicated VM cores). That’s I suppose a simplification they can make by focusing only on “datacenter” while intel needs the same design to work from 1 socket to hundreds.
- walrus01 5y agoI realize it's probably targeted at hyperscale "cloud" stuff, but when their previous CPU was announced, I took a good long and hard look at what it would take to actually buy and use it. Unlike being able to buy a $650 Supermicro, MSI or Tyan dual socket motherboard and put your choice of a couple of Intel or AMD CPUs on it, it turned out that it was unavailable for mere mortals to purchase at any reasonable price. My message for people trying to make "ARM Server" CPUs a thing is that you have a real chicken or egg problem to solve, getting these things into the hands of people doing Linux development on x86-64 right now. Without a robust ecosystem of all the Taiwan-based motherboard manufacturers behind you, it's never going to get more than a few percent market share.
- mcqueenjordan 5y agoSame. I'd love to throw together one or two 1U servers with an Ampere chip, but I could not find a single way to buy one.
- walrus01 5y agoThis is exactly the same thing that happened several years prior to Ampere, with other "ARM Server" CPU vendor offerings. I thing it turned out that the only thing I could purchase was a $3000 cpu and motherboard kit that were significantly slower and weaker than a $350 core i7 on a $120 motherboard (at the time, this was at least 3.5 to 4 years ago).
- LargoLasskhyfv 5y agoI think you mistake marketshare with mindshare. The devs can play with Raspberry Pies or similar, because why not, it runs AARCH64, don't it? The few devs who really need deep system level access are either paid, or get devkits. Meanwhile, 'the market' IS the hyperscalers. Nobody cares about the few nerds wetting themselves. They can go gaming, obsess over retrocomputing, toolkits, theming, /r/unixporn, whatever.
- KingOfCoders 5y agoI do think getting it in the hand of more people, more people will run it and say "yes, works" and then take it into consideration when making architecture/purchasing decisions. I've been a CTO for a decade+ and did try to get one the last time they made a splash.
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- saagarjha 5y agoWas wondering where they got their architectural license; it seems like they somehow obtained it indirectly from Applied Micro? Does anyone have more details as to how/when they acquired one?
- ksec 5y agoI dont think anyone would know and I am not sure why that is important. And it is not like it needs some secret deal or special case for a company to acquire architectural license. Not to mention ARM is an investor in Ampere.
- saagarjha 5y agoArchitectural licenses are often secret deals, with the licensee being anonymous in many cases. As they are handed out fairly rarely, I personally find them fairly interesting to follow along.
- Aissen 5y agoMy understanding is that this PR session is basically the announcement of the deal. True, it would be nice to know how long they've had a deal, but IMHO it's more interesting to know for how long the team has been working on the new design, and when it's slated to launch.
- ksec 5y agoFrom the article >In fact, Ampere explains that what the move towards a full custom microarchitecture core design was actually always the plan for the company since its inception, and their custom CPU design had been in the works for the past 3+ years. So my guess is that they always had the license but never put out the announcement until they actually have their custom core. Although in modern days PR speak a "custom" core could also be a custom ARM X-1 [1] type of custom. We will have to wait for more details. [1] https://www.arm.com/products/cortex-x https://www.arm.com/products/cortex-x
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- ksec 5y ago>Microsoft in particular is a big addition to the customer list, Google are working on their own ARM Server Chip. And we finally have ( some sort of ) confirmation Microsoft will be using Ampere. At least Ampere will have fixed their Go to Market problem where no hyperscaler were committed to buying ARM instead of building their own. Along with Tencent Cloud which is a big surprise. Which got me to question why Marvell lost the battle to Ampere.
- StreamBright 5y agoWhat does this mean from the software support point of view? Do we need a new target architecture in compilers?
- emteycz 5y agoThe ISA remains the same. This is one level down, how the CPU itself works - ISA instructions are turned to micro instructions.
- mhh__ 5y agoTarget no(technically yes depending on what features it implements etc.), set of tuning parameters yes.
- wyldfire 5y agoMicroarchitectures are used in -mtune= so there's an opportunity to tweak compilers to suit this design. But no changes are required: Aarch64 support is already present in popular compilers.
- baybal2 5y agoImportant note X-Gene already used own cores long time ago, so it's non-news. They also had two from-scratch developed microarchitectures.
- floatboth 5y agoWell, the first Ampere product (eMAG) was based on the last X-Gene, and it was way behind contemporary Cortex/Neoverse cores. It is news that they took the time and effort to continue with custom uarch development, that they have confidence in the ability to make a good one.
- IanCutress 5y agoAmpere were all in with N1, and it seemed that they'd stay with the Neoverse ecosystem for several generations. Everything coming out of them contact wise was very much Neoverse related, so for them to get up and say that they're ditching Neoverse after one generation is big news. Still SBSA compliant, but big news. Renee and Atiq brought over a lot of Intel SoC designers when they left.
- Teongot 5y agoIf all the companies doing custom AArch64 microarchitectures had spent the effort building systems around ARM's designs instead, we'd probably have a thriving ARM server ecosystem by now.
- gsnedders 5y agoMost of the custom AArch64 implementations are only semi-custom; they're mostly just derivatives of the ARM designs. The AWS Graviton chips are some of the few that are just using the ARM designs. I don't think it's the wrong option for most of these companies; the ARM designs are really designed with a bit too much of a focus on power consumption and die area for server applications. The Neoverse V1 is the first ARM design really targeted at that market, and is shipping late this year AIUI. (That said, the Neoverse N2 is shipping not much later, and is a generation newer design, so we might end up with more N2 than V1, despite the V1 being a higher end part.)
- k__ 5y agoHow much do you think the industry can push RISC in terms of performance? Apple and AWS seem to leave the competition behind.
- api 5y agoI hereby declare that the coming ARM core wars will be termed "ARM wrestling." Please, please, hold the applause...
- mastax 5y agoI'm surprised. There have been many failures in the past to outdo ARM's cores: Intel, AMD, Nvidia, Samsung, Qualcomm. Granted, some of those are ancient history or were more management failures than technical failures. It seemed to me that with ARM finally focusing on developing high performance cores, and the success of N1, the industry would coalesce around that. ARM has control over the ISA development which can influence and be influenced by microarchitecture designs, though they do work with Apple and Fujitsu somewhat. ARM gets to combine license fees from many customers into a single large R&D budget, much like TSMC. There's a huge risk that you spend billions for years and end up with custom cores that are worse than what ARM puts out. So why design custom cores? Maybe it's a necessity for a viable CPU company. Maybe it's too easy to create a custom CPU with stock ARM cores so unless you can do substantially better than that, all your biggest potential customers will just make their own: Amazon, Microsoft, IBM, Oracle, Baidu, Google, Tencent, Alibaba, are all perfectly capable of putting some stock cores together. Yes, the devil is in the details but I don't think the details are enough to base a company around. Maybe even if making a better microarchitecture is unlikely you have to try or be doomed to failure in the long run. Maybe they believe their engineering is better. It's tempting to discount the value of individual contributors in projects involving hundreds or thousands of people. Maybe Ampere believe their engineers and/or managers are just better than the competition, and can beat them with fewer resources. Maybe it's not as hard as it used to be. The received wisdom after decades of Intel dominance was to not even try to compete. Now we seem to be reaching a plateau in microarchitecture innovation. Yes, CPUs are still getting faster but the designs seem to have converged a lot. It certainly seems easier to catch up given that Apple, ARM, and AMD have all succeeded recently. Ampere also starts with an A so they're in good company. Maybe it doesn't actually have to be substantially better. Maybe the N1 license fees are high and they just need something similar for less money. Maybe they just need something different that their sales team can sell as being better.
- Veedrac 5y ago*Arm Subtle but significant difference. The company is sentence case now.
- lowbloodsugar 5y agoAnd the logo is "arm"! WTF!
- ngcc_hk 5y agoThe two big chinese cloud provider ... tencent ... are these the reason to do non Arm to avoid sanction ? Wonder.