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> 3) designing and implementing CISC is difficult and takes long time — that's true... but designing and implementing a highly performant RISC is also quite dif

by hajile 3y ago

> 3) designing and implementing CISC is difficult and takes long time — that's true... but designing and implementing a highly performant RISC is also quite difficult and takes a long time, and today the difference is mainly in the decoding stage: after it, its all RISC-like microinstructions in either case; You are massively understating this. Tenstorrent has ~280 people. They are working on 2-3 CPU designs, 2-3 AI accelerators, all the IO stuff, etc. A decent percentage of these people will have to be dedicated to testing, marketing, HR, finances, legal, etc. Jim Keller projects their 8-wide Ascalon to be competitive with the upcoming Zen5 core. I'll guarantee you that the Zen 5 core has way more than 280 people working on it. Even if Ascalon were just 70% of the performance of Zen 5, that would put it around Zen 2 performance and that core also required hundreds to thousands of people. This is an R&D economic disparity that cannot be sustained. This isn't limited to Tenstorrent either, Nuvia had around 300 people when it was acquired and the Qualcomm Oryon also seems to be competitive with x86 for a fraction of the R&D cost.

fpgamlirfanboy 3y ago
i don't have an outrageous amount of experience here but i work at a place that designs and sells x86 chips (and i work on arch adjacent things). i'll just say this: do not underestimate the effect of institutional friction/momentum/complacency on "time to ship". point being: maybe RISC is more "agile" than CISC but also maybe Tenstorrent could have chosen a CISC approach and still iterated quickly simply because they're not an institution. edit: > They are working on 2-3 CPU designs, 2-3 AI accelerators, all the IO stuff, etc also do we actually know how much they're designing wholecloth and not buying off the shelf? edit2: i think Tenstorrent is great and i'll probably buy a devkit soon (as well as maybe apply lol...)
- The_Colonel 3y ago
  Yeah, I don't buy this argument either. Startups like that often have the best handpicked people, won't be burdened by established processes, won't need segmentation, chips designed for specific customers / use cases, doesn't have a brand to protect abd generally can act aggresively / risky. It's kind of like comparing Photopea with Photoshop, the former being developed by a single person, and then claiming this huge productivity difference is caused by Photopea using Javascript (vs. C++ for Photoshop).
klelatti 3y ago
> This is an R&D economic disparity that cannot be sustained. AMD already has enormous scale that it can spread development costs over. Tenstorrent won’t ‘win’ vs AMD solely because it needs fewer engineers and that reduces development costs (it might win for other reasons but that’s a separate argument). Even if it does make a cheaper product then you have to take into account the fact that you’re asking hundreds of millions of users to switch ISAs with the corresponding economic costs in return for a small reduction in the purchase price.
- hajile 3y ago
  AMD and Intel are high-margin rather than high-volume products. AMD shipped 8M chips in Q4 of 2023 and Intel shipped 50M (not what the tech press would have you believe given how they rave about Zen). Even if we assume they shipped that many every quarter (Q4 is the high water mark), that's 32M chips for AMD and another 200M for Intel. Apple sold 235M smartphones in 2023 and total smartphone sales were around 1.2B. Apple alone outsold Intel and AMD combined and Apple is shipping their high-end cores in every one of those devices. Put simply, AMD and Intel aren't the big boys anymore. Everything you say about AMD/Intel's economies of scale apply even more to the rest of the industry. Why would a company make a risky expansion into the race-to-the-bottom Wintel market when the phone and server/AI markets are easier to penetrate and offer a great combination of massive economies of scale and super-high margins? Qualcomm is only trying to enter the PC market because they are dominating the phone market and are looking to expand their business. RISC-V won't be entering until ARM has done the hard part of forcing more ISA flexibility onto devs.
UncleOxidant 3y ago
> I'll guarantee you that the Zen 5 core has way more than 280 people working on it. And I'll postulate that however many people AMD has working on a new CPU, Intel probably has at least 2X that many. Part of this is just due to the inertia at Intel, part of it is likely due to Keller being successful at streamlining the AMD design process while he had to give up on that at Intel due to that institutional inertia. Would Intel be any more efficient if they were designing a RISC-V processor or would they still suffer from the same institutional inertia? I suspect the latter.
- hajile 3y ago
  Your argument is that this is the only difference. If so, then Tenstorrent should have chosen x86. They could support all the way through SSE3 without patent negotiations and maintain backward compatibility rather than risking it on a new ISA. Why didn't they? The same reason that software devs don't want to implement a bad API that's been continually updated for years. A new API allows you a chance to do things better even if both APIs technically do the same exact things. You can move quickly and confidently spending that mental energy and time on things like performance instead of contemplating weird edge cases and writing endless tests for each of them. The same applies to Tenstorrent and RISC-V. The cleaner ISA means you don't have to sit around thinking about how an instruction can be potentially executed for a weird side effect and how that will propagate through the pipeline. Instead, you can focus that mental energy on performance enhancing changes. In any case though, Intel sells 6-7x more chips than AMD, so even with 2x the people, their economies of scale are still better. That said, I believe a cleanroom RISC-V design by Intel would still progress faster at Intel than x86 does and it would probably require fewer people allowing them to put the rest on other projects and the overall reduction in team size might even further increase the design rate (as you've stated).
  - UncleOxidant 3y ago
    No Tenstorrent wouldn't have any advantage in choosing x86. My argument is that Intel as an organization would still face the same institutional inertia if they developed a RISC-V cpu as they do with their x86 cpus. > that said, I believe a cleanroom RISC-V design by Intel would still progress faster at Intel than x86 Possibly. But it would still take a lot longer than Tenstorrent or even AMD (should they decide to do this). There's a lot of tasks that Intel tends to throw bodies at that an AMD or Tenstorrent have automated.

by hajile 3y ago

fpgamlirfanboy 3y ago

i don't have an outrageous amount of experience here but i work at a place that designs and sells x86 chips (and i work on arch adjacent things). i'll just say this: do not underestimate the effect of institutional friction/momentum/complacency on "time to ship". point being: maybe RISC is more "agile" than CISC but also maybe Tenstorrent could have chosen a CISC approach and still iterated quickly simply because they're not an institution. edit: > They are working on 2-3 CPU designs, 2-3 AI accelerators, all the IO stuff, etc also do we actually know how much they're designing wholecloth and not buying off the shelf? edit2: i think Tenstorrent is great and i'll probably buy a devkit soon (as well as maybe apply lol...)

The_Colonel 3y ago
Yeah, I don't buy this argument either. Startups like that often have the best handpicked people, won't be burdened by established processes, won't need segmentation, chips designed for specific customers / use cases, doesn't have a brand to protect abd generally can act aggresively / risky. It's kind of like comparing Photopea with Photoshop, the former being developed by a single person, and then claiming this huge productivity difference is caused by Photopea using Javascript (vs. C++ for Photoshop).

klelatti 3y ago

> This is an R&D economic disparity that cannot be sustained. AMD already has enormous scale that it can spread development costs over. Tenstorrent won’t ‘win’ vs AMD solely because it needs fewer engineers and that reduces development costs (it might win for other reasons but that’s a separate argument). Even if it does make a cheaper product then you have to take into account the fact that you’re asking hundreds of millions of users to switch ISAs with the corresponding economic costs in return for a small reduction in the purchase price.

hajile 3y ago
AMD and Intel are high-margin rather than high-volume products. AMD shipped 8M chips in Q4 of 2023 and Intel shipped 50M (not what the tech press would have you believe given how they rave about Zen). Even if we assume they shipped that many every quarter (Q4 is the high water mark), that's 32M chips for AMD and another 200M for Intel. Apple sold 235M smartphones in 2023 and total smartphone sales were around 1.2B. Apple alone outsold Intel and AMD combined and Apple is shipping their high-end cores in every one of those devices. Put simply, AMD and Intel aren't the big boys anymore. Everything you say about AMD/Intel's economies of scale apply even more to the rest of the industry. Why would a company make a risky expansion into the race-to-the-bottom Wintel market when the phone and server/AI markets are easier to penetrate and offer a great combination of massive economies of scale and super-high margins? Qualcomm is only trying to enter the PC market because they are dominating the phone market and are looking to expand their business. RISC-V won't be entering until ARM has done the hard part of forcing more ISA flexibility onto devs.

UncleOxidant 3y ago

> I'll guarantee you that the Zen 5 core has way more than 280 people working on it. And I'll postulate that however many people AMD has working on a new CPU, Intel probably has at least 2X that many. Part of this is just due to the inertia at Intel, part of it is likely due to Keller being successful at streamlining the AMD design process while he had to give up on that at Intel due to that institutional inertia. Would Intel be any more efficient if they were designing a RISC-V processor or would they still suffer from the same institutional inertia? I suspect the latter.

hajile 3y ago
Your argument is that this is the only difference. If so, then Tenstorrent should have chosen x86. They could support all the way through SSE3 without patent negotiations and maintain backward compatibility rather than risking it on a new ISA. Why didn't they? The same reason that software devs don't want to implement a bad API that's been continually updated for years. A new API allows you a chance to do things better even if both APIs technically do the same exact things. You can move quickly and confidently spending that mental energy and time on things like performance instead of contemplating weird edge cases and writing endless tests for each of them. The same applies to Tenstorrent and RISC-V. The cleaner ISA means you don't have to sit around thinking about how an instruction can be potentially executed for a weird side effect and how that will propagate through the pipeline. Instead, you can focus that mental energy on performance enhancing changes. In any case though, Intel sells 6-7x more chips than AMD, so even with 2x the people, their economies of scale are still better. That said, I believe a cleanroom RISC-V design by Intel would still progress faster at Intel than x86 does and it would probably require fewer people allowing them to put the rest on other projects and the overall reduction in team size might even further increase the design rate (as you've stated).
- UncleOxidant 3y ago
  No Tenstorrent wouldn't have any advantage in choosing x86. My argument is that Intel as an organization would still face the same institutional inertia if they developed a RISC-V cpu as they do with their x86 cpus. > that said, I believe a cleanroom RISC-V design by Intel would still progress faster at Intel than x86 Possibly. But it would still take a lot longer than Tenstorrent or even AMD (should they decide to do this). There's a lot of tasks that Intel tends to throw bodies at that an AMD or Tenstorrent have automated.