Nvidia to Acquire Arm for $40B • Hacker News Board

Re: Nvidia to Acquire Arm for $40B

#301

Post by drivebycomment » Mon, Sep 14, 2020, 3:50 AM UTC

dahart wrote: post #260

drivebycomment wrote: post #205

Earlier quoted context omitted.

You're not wrong, but most of HN threads are like this. 80% of comments are low information, Dunning-Kruger effect in action. But among that, there are still some useful gems, so despite what you said, HN is still worth it. If you fold the first two top level comments, the rest have some useful , informed perspective. I don't see this as having that much of an impact on any short to medium term. ARM has too much intr…

> Humanity would be better off of a single ISA does become truly universal. This is an interesting thought. I think I would agree with this in the CPU world of the last 20-30 years, but it makes me wonder a few things. Might a universal ISA eliminate major pieces of competitive advantage for chip makers, and/or stall innovation? It does feel like non-vector instructions are somewhat settled, but vector instructions h…

> Might a universal ISA eliminate major pieces of competitive advantage for chip makers, and/or stall innovation?

That's a good question. I didn't try to put all the necessary nuances in a single sentence, so you're right to question a lot of the unsaid assumptions. I don't know for sure at this point the innovation in ISA has run most of its course yet, but I do feel like we kind of have, given how relatively little difference it makes. I think a "truly" universal ISA, if it ever happens, would necessarily have to have a governance and evolution cycles, so that people will have to agree to the core part of the universal ISA, yet have a room and a way to let others experiment various extensions, including vector extensions for example, and have a process to reconcile and agree on the standard adoption. I don't know if that's actually possible - it might be very difficult or impossible for many different reasons. But if such can happen, that would be beneficial, as it would reduce certain amount of duplication, and unlock certain new possibilities.

> Please consider erasing the term "Dunning-Kruger effect" from your mind. It is being used here incorrectly

Duly noted.

Re: Nvidia to Acquire Arm for $40B

#302

Post by darksaints » Mon, Sep 14, 2020, 3:51 AM UTC

anarazel wrote: post #287

darksaints wrote: post #142

Earlier quoted context omitted.

OpenPOWER is pretty awesome but would be nowhere near as awesome as an OpenItanium. IMHO, Itanium was always mismarketed and misoptimized. It made a pretty good server processor, but not so good that enterprises were willing to migrate 40 year old software to run on it. In mobile form, it would have made a large leap in both performance and battery life. And it would have been a fairly easy market to break into: the…

IMO VLIW is an absurdly bad choice for a general purpose processor. It requires baking in a huge amount of low level micro-architectural details into the compiler / generated code. Which obviously leads to problems with choosing what hardware generation to optimize for / not being able to generate good code for future architectures. And the compiler doesn't even come close to having as much information as the CPU has…

Traditional compiler techniques may have struggled with maintaining code for different architectures, but a lot has changed in the last 15 years. The rise of widely used IR languages has led to compilers that support dozens of architectures and hundreds of instruction sets. And they are getting better all the time.

The compiler has nearly all of the information that the CPU has, and it has orders of magnitude more. At best, your CPU can think a couple dozen cycles ahead of what it is currently executing. The compiler can see the whole program, can analyze it using dozens of methodologies and models, and can optimize accordingly. Something like Link Time Optimization can be done trivially with a compiler, but it would take an army of engineers decades of work to be able to implement in hardware.

Re: Nvidia to Acquire Arm for $40B

#303

Post by dragontamer » Mon, Sep 14, 2020, 3:52 AM UTC

anarazel wrote: post #287

darksaints wrote: post #142

Earlier quoted context omitted.

OpenPOWER is pretty awesome but would be nowhere near as awesome as an OpenItanium. IMHO, Itanium was always mismarketed and misoptimized. It made a pretty good server processor, but not so good that enterprises were willing to migrate 40 year old software to run on it. In mobile form, it would have made a large leap in both performance and battery life. And it would have been a fairly easy market to break into: the…

IMO VLIW is an absurdly bad choice for a general purpose processor. It requires baking in a huge amount of low level micro-architectural details into the compiler / generated code. Which obviously leads to problems with choosing what hardware generation to optimize for / not being able to generate good code for future architectures. And the compiler doesn't even come close to having as much information as the CPU has…

VLIW was the best implementation (20 years ago) of instruction level parallelism.

But what have we learned in these past 20 years?

* Computers will continue to become more parallel -- AMD Zen2 has 10 execution pipelines, supporting 4-way decode and 6-uop / clock tick dispatch per core, with somewhere close to 200 registers for renaming / reordering instructions. Future processors will be bigger and more parallel, Ice Lake is rumored to have over 300-renaming registers.

* We need assembly code that scales to all different processors of different sizes. Traditional assembly code is surprisingly good (!!!) at scaling, thanks to "dependency cutting" with instructions like "xor eax, eax".

* Compilers can understand dependency chains, "cut them up" and allow code to scale. The same code optimized for Intel Sandy Bridge (2011-era chips) will continue to be well-optimized for Intel Icelake (2021 era) ten years later, thanks to these dependency-cutting compilers.

I think a future VLIW chip can be made that takes advantage of these facts. But it wouldn't look like Itanium.

----------

EDIT: I feel like "xor eax, eax" and other such instructions for "dependency cutting" are wasting bits. There might be a better way for encoding the dependency graph rather than entire instructions.

Itanium's VLIW "packages" is too static.

I've discussed NVidia's Volta elsewhere, which has 6-bit dependency bitmasks on every instruction. That's the kind of "dependency graph" information that a compiler can provide very easily, and probably save a ton on power / decoding.

Re: Nvidia to Acquire Arm for $40B

#304

Post by StillBored » Mon, Sep 14, 2020, 3:54 AM UTC

darksaints wrote: post #226

drivebycomment wrote: post #188

Earlier quoted context omitted.

Itanuim deserved its fiery death and resurrection doesn't make any sense whatsoever. It's a dead end architecture, and humanity gained (by freeing up valuable engineering power to other more useful endeavors) when it died.

Itanium was an excellent idea that needed investment in compilers. Nobody wanted to make that investment because speculative execution got them 80% of the way there without the investment in compilers. But as it turns out, speculative execution was a phenomenally bad idea, and patching its security vulnerabilities has set back processor performance to the point where VLIW seems like a good idea again. We should have…

I think your conflating OoO and speculative execution. It was OoO which the itanium architects (apparently) didn't think would work as well as it did. OoO and being able to build wide superscaler machines, which could dynamically determine instruction dependency chains is what killed EPIC.

Speculative execution is something you would want to do with the itanium as well, otherwise the machine is going to be stalling all the time waiting for branches/etc. Similarly, later itaniums went OoO (dynamically scheduled) because it turns out, the compiler can't know runtime state..

https://www.realworldtech.com/poulson/

Also while googling for that, ran across this:

https://news.ycombinator.com/item?id=21410976

PS: speculative execution is here to stay, it might be wrapped in more security domains and/or its going to just be one more nail in the business model of selling shared compute (something that was questionably from the beginning).

Re: Nvidia to Acquire Arm for $40B

#305

Post by dragontamer » Mon, Sep 14, 2020, 3:54 AM UTC

darksaints wrote: post #302

anarazel wrote: post #287

Earlier quoted context omitted.

IMO VLIW is an absurdly bad choice for a general purpose processor. It requires baking in a huge amount of low level micro-architectural details into the compiler / generated code. Which obviously leads to problems with choosing what hardware generation to optimize for / not being able to generate good code for future architectures. And the compiler doesn't even come close to having as much information as the CPU has…

Traditional compiler techniques may have struggled with maintaining code for different architectures, but a lot has changed in the last 15 years. The rise of widely used IR languages has led to compilers that support dozens of architectures and hundreds of instruction sets. And they are getting better all the time. The compiler has nearly all of the information that the CPU has, and it has orders of magnitude more. A…

> At best, your CPU can think a couple dozen cycles ahead of what it is currently executing.

The 200-sized reorder buffer says otherwise.

Loads/stores can be reordered for 200+ different concurrent objects on modern Intel skylake (2015 through 2020) CPUs. And its about to get a bump to 300+ sized reorder buffers in Icelake.

Modern CPUs are designed to "think ahead" almost the entirety of DDR4 RAM Latency, allowing reordering of instructions to keep the CPU pipes as full as possible (at least, if the underlying assembly code has enough ILP to fill the pipelines while waiting for RAM).

> Something like Link Time Optimization can be done trivially with a compiler, but it would take an army of engineers decades of work to be able to implement in hardware.

You might be surprised at what the modern Branch predictor is doing.

If your "call rax" indirect call constantly calls the same location, the branch predictor will remember that location these days.

Re: Nvidia to Acquire Arm for $40B

#306

Post by zdw » Mon, Sep 14, 2020, 3:54 AM UTC

AnthonyMouse wrote: post #175

zdw wrote: post #73

I see this going a few ways for different players: The perpetual architecture license folks that make their own cores like Apple, Samsung, Qualcomm, and Fujitsu (I think they needed this for the A64FX, right?) will be fine, and may just fork off on the ARMv8.3 spec, adding a few instructions here or there. Apple especially will be fine as they can get code into LLVM for whatever "Apple Silicon" evolves into over time…

> The perpetual architecture license folks that make their own cores like Apple, Samsung, Qualcomm, and Fujitsu (I think they needed this for the A64FX, right?) will be fine There is one thing they would need to worry about though, which is that if the rest of the market moves to RISC-V or x64 or whatever else, it's not implausible that someone might at some point make a processor which is superior to the ones those…

> Their best move might be to forget about the architecture license and make the switch to something else with the rest of the market.

This assumes that there isn't some other factor in transitioning architecture - this argument could boil down in the mid 2000's to "Why not go x86/amd64", but you couldn't buy a license to that easily (would need to be 3-way with Intel/AMD to further complicate things)

Apple has done quite well with their ARM license, outperforming the rest of the mobile form factor CPU market by a considerable margin. I don't doubt that they could transition - they've done it successfully 3 times already, even before the current ARM transition.

Apple under Cook has said they want to "to own and control the primary technologies behind the products we make". I doubt they'd turn away from that now to become dependent on an outside technology, especially given how deep their pockets are.

Re: Nvidia to Acquire Arm for $40B

#307

Post by broknbottle » Mon, Sep 14, 2020, 3:55 AM UTC

beervirus wrote: post #150

throw_m239339 wrote: post #139

Tangential, but when I hear about all these insane "start-up du jour" valuations, does anyone else feel like $40B isn't a lot of a hardware company sur as ARM?

$40 billion is a real valuation though, as opposed to WeWork’s.

are you suggesting a bunch of office space leases that are fully stocked with beer is not worth $40 billion?

Re: Nvidia to Acquire Arm for $40B

#308

Post by salawat » Mon, Sep 14, 2020, 3:55 AM UTC

ericmay wrote: post #26

maxioatic wrote: post #14

> Immediately accretive to NVIDIA’s non-GAAP gross margin and EPS Can someone explain this? (From the bullet points of the article) I looked up the definition of accretive: "characterized by gradual growth or increase." So it seems like they expect this to increase their margins. Does that mean ARM had better margins than NVIDIA? Edit: I don't know what non-GAAP and EPS stand for

EPS -> earnings per share Non-GAAP -> doesn’t follow generaly accepted accounting practices. There are alternative accounting methods. GAAP is very US-centric (not good or bad, just stating a fact).

Though note the intent of GAAP is to cut down on "creative accounting" which can tend to mislead.

Re: Nvidia to Acquire Arm for $40B

#309

Post by justicezyx » Mon, Sep 14, 2020, 3:56 AM UTC

llukas wrote: post #259

justicezyx wrote: post #132

Earlier quoted context omitted.

The comment identified the positive side of the nvidia story. Note that nvidia had not had large acquisition for many years. This acquisition can be seen as a beacon of nvidia's past struggle against the market and the competitors. For whatever happened, nvidia innovated to their success, and had enabled possibly the biggest tech boom so far through deep learning. Might be one day everyone claimed nvidia to be the "m…

> The comment identified the positive side of the nvidia story. Note that nvidia had not had large acquisition for many years. Not correct Mellanox was bought for $7B.

Bad me... Poor memory!

Re: Nvidia to Acquire Arm for $40B

#310

Post by arp242 » Mon, Sep 14, 2020, 3:56 AM UTC

QuixoticQuibit wrote: post #270

arp242 wrote: post #236

Earlier quoted context omitted.

I don't really have an opinion on nVidia, as I haven't dealt with any of their products for over a decade; my own problem with this is somewhat more abstract: I'm not a big fan of this constant drive towards merging all these tech companies (or indeed, any company really). Perhaps there are some short-term advantages for the ARM platform, but on the long term it means a few small tech companies will have all the powe…

I don’t disagree with you, but I see it two ways: 1. The continued conglomeratization in the tech sector is a worrying trend as we see fewer and fewer small players. 2. Only a large-ish company could provide effective competition in the CPU/ISA/architecture space against the current x86 duopoly.

I'm not so sure about that second point; I don't see why an independent ARM couldn't provide an effective competition? Server ARMs have been a thing for a while, and Apple has been working on ARM macbooks for a while. I believe the goal is even to completely displace Intel macBooks in favour of the ARM ones eventually.

The big practical issue is probably software compatibility and the like, and it seems to me that the Apple/macOS adoption will do more for that than nVidia ownership.