6 ms·

What exactly is the selling point of the Power ISA? Why would I want to use it over RISC-V?

Symmetry 1y ago
You can accomplish the same task in substantially fewer instructions, leading to higher performance for a given level of design effort. Also a more developed software ecosystem.
- snvzz 1y ago
  >You can accomplish the same task in substantially fewer instructions, leading to higher performance for a given level of design effort. The statement is true and favorable to RISC-V, as it is the one with lowest instruction count and code size; RISC-V wins, and it is not even close. >Also a more developed software ecosystem. Historically true, but right now the momentum is with RISC-V, and it is absolutely is catching up, and no longer a point of contention. e.g. Debian is the largest Linux distribution by its library of packaged software. There, RISC-V has already overtaken[0] it in available package count. 0. https://buildd.debian.org/stats/graph-week-big.png https://buildd.debian.org/stats/graph-week-big.png
bhouston 1y ago
It is aimed at a completely different market from RISC-V. RISC-V advantages is that it is an incredible simple and extensible architecture aimed at low power / embedded use cases. It is also easy to customize (similar to ARM) for specific use cases. Power ISA is a super computer chip, while RISC-like, has a lot of legacy baggage and isn't designed for low-power nor is it designed for embedded situations. It also is not designed for customizability, it is more like a monolith project. Power ISA will have space at the top of the market for very high performance CPUs. But I think it will be stuck there as there are no benefits over RISC-V in the areas where RISC-V is growing right now.
- orbifold 1y ago
  That isn’t actually true. I‘ve personally worked on an embedded POWER processor https://github.com/electronicvisions/nux https://github.com/electronicvisions/nux. It is used as a dual core embedded micro-controller in a neuromorphic chip. Each core has just 16kB of memory on chip and 4kB instruction cache. POWER has subsets of the instruction set which have a gcc and llvm target and are well suited for embedded use cases. Main advantage of RISCV at this point is that it has a larger community. But at the time it didn’t even have a vector instruction set, whereas we could easily modify the POWER one for our purposes.
- panick21_ 1y ago
  RISC-V is absolutely not and never has been 'aimed at low power / embedded'. Literally from the very beginning the target was 'be an ISA for everything'. Its just natural that simpler things were standardized first and came to market first. That POWER is better at top of the market is highly questionable, every new startup coming into the high performance space has universally picked RISC-V over OpenPOWER. Also, nowadays even complex ISA were fine for embedded. The cost difference for stuff like that is tiny. Its really just about how many options do you have in the market, both open and closed. And that's where RISC-V by now simply has more. OpenPOWER was only fake open for a long time, while marketing itself as open. Only when they were totally getting crushed, did they update and are more like RISC-V, but it was many years to late.
  - bhouston 1y ago
    > Its just natural that simpler things were standardized first and came to market first. Which isn't that different than what I am saying. RISC-V is marketing towards low-power/embedded right now because it doesn't have performant cores. https://benhouston3d.com/blog/risc-v-in-2024-is-slow https://benhouston3d.com/blog/risc-v-in-2024-is-slow Power ISA was not focused on this market, its historical market was high performance computing.
    - dragontamer 1y ago
      Freescale PowerQUICC fans say whaaaaaat? Power ISA absolutely was used in embedded contexts for years. Decades even. --------- Instruction sets aren't very important actually. Like yeah, compiler infrastructure helps but a lot of embedded decision making is about peripherals. PowerQUICC had powerful and extendable I/O that could be customized to many different needs. And I believe the bulk of those benefits stay over to the updated ARM chip QorIQ (as NXP bought FreeScale and seems to have prioritized ARM).
      - adrian_b 1y ago
        After Motorola has abandoned totally (MC88k, M.core) or partially (MC68k => Coldfire) its older ISAs and it has transitioned to using the POWER/PowerPC ISA, it has applied it to the market in which they was interested, designing many kinds of microcontrollers with it, mainly for the automotive and communications markets, where microcontrollers with higher performance were required. Around the same time IBM has also introduced a series of microcontrollers based on the POWER ISA (PowerPC 4xx). However, when the POWER ISA has initially been designed, before its launch in 1990, its target were high-end scientific workstations and servers made by IBM. The idea of using it in embedded computers has come much later, when the increased density achievable in integrated circuits has made that possible.
- snvzz 1y ago
  >It is aimed at a completely different market from RISC-V. Not possible. RISC-V is aimed at absolutely everything. Thus leaving no sizable niche exclusive to POWER ISA.
irusensei 1y ago
I feel like regardless of what you can accomplish with it will be drowned by having to deal with IBM's brilliant handling of their products. The only occasions I interacted with POWER was in projects where the client was happily deploying bog standard enterprise amd64 servers running Linux to replace it.

You can accomplish the same task in substantially fewer instructions, leading to higher performance for a given level of design effort. Also a more developed software ecosystem.

snvzz 1y ago
>You can accomplish the same task in substantially fewer instructions, leading to higher performance for a given level of design effort. The statement is true and favorable to RISC-V, as it is the one with lowest instruction count and code size; RISC-V wins, and it is not even close. >Also a more developed software ecosystem. Historically true, but right now the momentum is with RISC-V, and it is absolutely is catching up, and no longer a point of contention. e.g. Debian is the largest Linux distribution by its library of packaged software. There, RISC-V has already overtaken[0] it in available package count. 0. https://buildd.debian.org/stats/graph-week-big.png https://buildd.debian.org/stats/graph-week-big.png

bhouston 1y ago

It is aimed at a completely different market from RISC-V. RISC-V advantages is that it is an incredible simple and extensible architecture aimed at low power / embedded use cases. It is also easy to customize (similar to ARM) for specific use cases. Power ISA is a super computer chip, while RISC-like, has a lot of legacy baggage and isn't designed for low-power nor is it designed for embedded situations. It also is not designed for customizability, it is more like a monolith project. Power ISA will have space at the top of the market for very high performance CPUs. But I think it will be stuck there as there are no benefits over RISC-V in the areas where RISC-V is growing right now.

orbifold 1y ago
That isn’t actually true. I‘ve personally worked on an embedded POWER processor https://github.com/electronicvisions/nux https://github.com/electronicvisions/nux. It is used as a dual core embedded micro-controller in a neuromorphic chip. Each core has just 16kB of memory on chip and 4kB instruction cache. POWER has subsets of the instruction set which have a gcc and llvm target and are well suited for embedded use cases. Main advantage of RISCV at this point is that it has a larger community. But at the time it didn’t even have a vector instruction set, whereas we could easily modify the POWER one for our purposes.
panick21_ 1y ago
RISC-V is absolutely not and never has been 'aimed at low power / embedded'. Literally from the very beginning the target was 'be an ISA for everything'. Its just natural that simpler things were standardized first and came to market first. That POWER is better at top of the market is highly questionable, every new startup coming into the high performance space has universally picked RISC-V over OpenPOWER. Also, nowadays even complex ISA were fine for embedded. The cost difference for stuff like that is tiny. Its really just about how many options do you have in the market, both open and closed. And that's where RISC-V by now simply has more. OpenPOWER was only fake open for a long time, while marketing itself as open. Only when they were totally getting crushed, did they update and are more like RISC-V, but it was many years to late.
- bhouston 1y ago
  > Its just natural that simpler things were standardized first and came to market first. Which isn't that different than what I am saying. RISC-V is marketing towards low-power/embedded right now because it doesn't have performant cores. https://benhouston3d.com/blog/risc-v-in-2024-is-slow https://benhouston3d.com/blog/risc-v-in-2024-is-slow Power ISA was not focused on this market, its historical market was high performance computing.
  - dragontamer 1y ago
    Freescale PowerQUICC fans say whaaaaaat? Power ISA absolutely was used in embedded contexts for years. Decades even. --------- Instruction sets aren't very important actually. Like yeah, compiler infrastructure helps but a lot of embedded decision making is about peripherals. PowerQUICC had powerful and extendable I/O that could be customized to many different needs. And I believe the bulk of those benefits stay over to the updated ARM chip QorIQ (as NXP bought FreeScale and seems to have prioritized ARM).
    - adrian_b 1y ago
      After Motorola has abandoned totally (MC88k, M.core) or partially (MC68k => Coldfire) its older ISAs and it has transitioned to using the POWER/PowerPC ISA, it has applied it to the market in which they was interested, designing many kinds of microcontrollers with it, mainly for the automotive and communications markets, where microcontrollers with higher performance were required. Around the same time IBM has also introduced a series of microcontrollers based on the POWER ISA (PowerPC 4xx). However, when the POWER ISA has initially been designed, before its launch in 1990, its target were high-end scientific workstations and servers made by IBM. The idea of using it in embedded computers has come much later, when the increased density achievable in integrated circuits has made that possible.
snvzz 1y ago
>It is aimed at a completely different market from RISC-V. Not possible. RISC-V is aimed at absolutely everything. Thus leaving no sizable niche exclusive to POWER ISA.

irusensei 1y ago

I feel like regardless of what you can accomplish with it will be drowned by having to deal with IBM's brilliant handling of their products. The only occasions I interacted with POWER was in projects where the client was happily deploying bog standard enterprise amd64 servers running Linux to replace it.