Comment by bhouston
1 year ago
RISC-V is not anywhere near competitive to ARM at the level that Qualcomm operates.
I’ve written about that here: https://benhouston3d.com/blog/risc-v-in-2024-is-slow
1 year ago
RISC-V is not anywhere near competitive to ARM at the level that Qualcomm operates.
I’ve written about that here: https://benhouston3d.com/blog/risc-v-in-2024-is-slow
Your otherwise on point piece contains the common misconception that ARM began in embedded systems. When they started they had a full computer system that had very competitive CPU performance for the time: https://en.m.wikipedia.org/wiki/Acorn_Archimedes
They pivoted to embedded shortly after spinning off into a separate company.
Not to be pedantic, but…
Acorn Computers started off much earlier (I owned an Acorn Atom when it was released) which begat the Electron, then the BBC Micro and then the Archimedes.
At that time ARM was just an architecture owned by Acorn. They created it with VSLI technology (Acorn’s Silicon partner) and used the first RISC chip in the BBC Micro before then pivoting it to the Archimedes.
Whilst Acorn itself was initially purchased by Olivetti, who eventually sold what remained years later to Morgan Stanley.
The ARM division was spun off as “Advanced RISC Machines” in a deal with both Apple, and VSLI Technology after Olivetti came onto the scene.
It is this company that we now know as Arm Holdings.
So it’s not entirely accurate to claim “they had a full computer system” as that was Acorn Computers, PLC.
Actually one of the first ARM spin off products was the 250 for Acorn, which was an entire Acorn computer system on a a chip.
Some of the other details you have are wrong too, to the point your comment is really quite misleading.
Anyone wanting an accurate version should check wikipedia: https://en.m.wikipedia.org/wiki/Acorn_Computers
(To be blunt the above comment is like a very bad LLM summary of the Acorn article).
It would be more accurate to say that there haven't been any RISC-V designs for Qualcomm's market segment yet.
As far as I am aware, there is nothing about the RISC-V architecture which inherently prevents it from ever being competitive with ARM. The people designing their own cores just haven't bothered to do so yet.
RISC-V isn't competitive in 2024, but that doesn't mean that it still won't be competitive in 2030 or 2035. If you were starting a project today at a company like Amazon or Google to develop a fully custom core, would you really stick with ARM - knowing what they tried to do with Qualcomm?
> RISC-V isn't competitive in 2024, but that doesn't mean that it still won't be competitive in 2030 or 2035.
We can't know and won't for up to until 2030 or 2035. Humans are just not very good when it comes projecting the future (if predictions of 1950-60's were correct, I would be typing this up from my cozy cosmic dwelling on a Jovian or a Saturnian moon after all).
History has had numerous examples when better ISA and CPU designs have lost out to a combination or mysteries and other compounding factors that are usually attributed to «market forces» (whatever that means to whomever). The 1980-90's were the heydays of some of the most brilliant ISA designs and nearly everyone was confident that a design X or Y would become dominant, or the next best thing, or anywhere in between. Yet, we were left with a x86 monopoly for several decades that has only recently turned into a duopoly because of the arrival of ARM into the mainstream and through a completely unexpected vector: the advent of smartphones. It was not the turn than anyone expected.
And since innovations tend to be product oriented, it is not possible to even design, leave alone build, a product with something does not exist yet. Breaking a new ground in the CPU design requires an involvement of a large number of driving and very un–mysterious (so to speak) forces, exorbitant investment (from the product design and manufacturing perspectives) that are available to the largest incumbents only. And even that is not guaranteed as we have seen it with the Itanium architecture.
So unless the incumbents commit and follow through, it is not likely (at least not obvious) that RISC-V will enter the mainstream and will rather remain a niche (albeit a viable one). Within the realms of possibility it can be assessed as «maybe» at this very moment.
A lot of the arguments I’m seeing ignore the factor that China sees ARM as a potential threat to it’s economic security and is leaning hard into risc-v. it’s silly to ignore the largest manufacturing base for computing devices when talking about the future of computing devices.
I would bet on china making risc-v the default solution for entry level and cost sensitive commodity devices within the next couple of years. It’s already happening in the embedded space.
The row with Qualcomm only validates the rationale for fast iterating companies to lean into riscv if they want to meaningfully own any of their processor IP.
The fact that the best ARM cores aren’t actually designed by ARM, but arm claims them as its IP is really enough to understand that migrating to riscv is eventually going to be on the table as a way to maximize shareholder value.
But then there is the software ecosystem issue.
Having a competitive CPU is 1% of the job. Then you need To have a competitive SoC (oh and not infringe IP), so that you can build the software ecosystem, which is the hard bit.
RISC-V is rapidly growing the strongest ecosystem.
The new (but tier1 like x86-64) Debian port is doing alright[0]. It'll soon pass ppc64 and close up to arm64.
0. https://buildd.debian.org/stats/graph-week-big.png
> But then there is the software ecosystem issue.
We still have problems with software not being optimised for Arm these days, which is just astounding given the prevalence on mobile devices, let alone the market share represented by Apple. Even Golang is still lacking a whole bunch of optimisations that are present in x86, and Google has their own Arm based chips.
Compilers pull off miracles, but a lot of optimisations are going to take direct experience and dedicated work.
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Not an issue because exceyt for a few windows or apple machines everthing arm is compiled and odds are they have the source. Give our ee a good risc-v and a couple years latter we will have our stuff rebult for that cpu
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We've seen compatibility layers between x86 and arm. Am I correct in thinking that a compatibility layer between riscV and arm would be easier/more performant since they're both risc architectures?
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> As far as I am aware, there is nothing about the RISC-V architecture which inherently prevents it from ever being competitive with ARM
Lack of reg+shifted reg addressing mode and or things like BFI/UBFX/TBZ
The perpetual promise of magic fusion inside the cores has not played out. No core exists to my knowledge that fuses more than two instructions at a time. Most of those take more than two to make. Thus no core exists that could fuse them.
Zba extension (mandatory in RVA23 profile) provides `sh{1,2,3}add rd, rs1, rs2` ie `rd = rs1 << {1,2,3} + rs2`, so a fusion with a subsequent load from `rd` would only require fusing two instructions.
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>would you really stick with ARM - knowing what they tried to do with Qualcomm?
Business are actually happen how the ALA is proven in court.
Your statement that "RISC-V in 2024 is slow" gets followed by a crazy sequitur that this will continue to be the case for a long time.
Ventana announced their second-gen Veyron 2 core at the beginning of this year and they are releasing a 192-core 4nm chip using it in 2025. They claim Veyron 2 is an 8-wide decoder with a uop cache allowing up to 15-wide issue and a 512-bit vector unit too. In raw numbers, they claim SpecInt per chip is significantly higher than an EPYC 9754 (Zen4) with the same TDP.
We can argue about what things will look like after it launches, but it certainly crushes the idea that RISC-V isn't going to be competing with ARM any time soon.
In my article I only say that it is currently slow and that there are various initiatives to make it fast and I am hopeful for the future.
The article ignores IP available for licensing, which is what is relevant in the context.
SoC designers choose from existing IP blocks, not from existing physical chips.
RISCV is an instruction set, but you compare ASICs
If qualcomm changes instruction decoding over you’ll likely see a dramatic difference
Not everyone is trying to make a chip for a phone. There are plenty of low compute applications which just need something.
Correct.
Also correct: RISC-V is not anywhere near competitive to ARM at the level that Qualcomm operates.
How is Geekbench any good at comparing RISC-V to ARM? Geekbench isn't a native RISC-V application, let alone has the wherewithal to correctly report any basic information like frequency or core count. You haven't even prefaced these either, and drew conclusions from them.
Also, actually searching the chip in question is impossible.
There are preview builds of Geekbench that are native RISC-V.
Doesn't mean that it is compiled with Vector support or optimizations, which is going to artificially make the results worse.
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But for many other customers, who might need something like an A0 core, it's a strong signal to consider RISC-V instead.
If you're talking physical chips you can buy off the shelf, sure.
But if you're talking IP, which would be what matters for the argument being made (core IP to use on new design), here's where we at (thanks to camel-cdr- on reddit[0]):
(rule of thumb SPEC2006*10 = SPEC2017)
SiFive P870-D: >18 SpecINT2006/GHz, >2 SpecINT2017/GHz
Akeana 5300: 25 SpecINT2006/GHz @ 3GHz
Tenstorrent Ascalon: >18 SpecINT2006/GHz, IIRC they mentioned targeting 18-20 at a high frequency
Some references for comparing:
Apple M1: 21.7 SpecINT2006/GHz, 2.33 SpecINT2017/GHz
Apple M4: 2.6 SpecINT2017/GHz
Zen5 9950x: 1.8 SpecINT2017/GHz
Current license-able RISC-V IP is certainly not slow.
0. https://www.reddit.com/r/hardware/comments/1gpssxy/x8664_pat...
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