6 ms·

From back when IA-64 (A.K.A. Itanium) was supposed to take Intel to the promised land.

by theandrewbailey 1mo ago

pjmlp 1mo ago
Without AMD, maybe it would have.
- shdwslrkr 1mo ago
  No, it wouldn't have. Without AMD rescuing x86, PowerPC wouldn't have died. MIPS wouldn't have died, and faces with the need to brake the 4Gn barrier on consumer equipment microsoft would have had windows running on three or four competing architectures until 2013 when everything would have switched to ARM. Itanium would have already been a rotting corpse. AMD rescued Intel from its own management.
  - pjmlp 1mo ago
    Sure it would, Windows XP 64 bits was alreary on Itanium, and NT versions for PowerPC and MIPS were already dead by then.
    - shdwslrkr 1mo ago
      First thank you for generously understanding my post despite the vandalism that autocorrect did to it. WindowsNT is remarkably well suited to porting to other arch. This was done on purpose to hedge against x86. Dead one day, reactivated the other. MS needed to brake the 4Gb barrier and they would have done anything to get consumer priced 64bit chips. Itanium was a dog. We had an Itanium SGI "supercomputer". Everything about it that SGI designed was amazing (hot swapping cpus). The cpu was a dog.
      - pjmlp 1mo ago
        Itanium wasn't set in stone, a few times CPUs were redesigned to fix architecture issues, naturally for WinIntel that became economic unfeasible the moment AMD64 became an alternative. Without it, Intel would most likely kept iterating and improving Itanium's architecture.
    - hedgehog 1mo ago
      It's unclear to me what would have likely happened had AMD stayed on IA32 and Netburst been uncontested. Itanium was far too expensive for consumer machines and it seems very possible that Intel would have fumbled IA64 in a way similar to more recent AVX-512 and their big.little efforts. Easy enough to port XP to Itanium, hard to get those machines into Best Buy or the Dell catalog in any way that makes sense. Had AMD continued Athlon performance improvements and Intel still responded with a P6-derived Pentium M (which even in our timeline was 32-bit) it still seems like there would have been no volume market for IA64 and we still would have eventually ended up with an evolution of IA32 even if it came from Intel instead of AMD.
      - pjmlp 1mo ago
        It is all what ifs by now, however I firmly believe if there was no other option other than Wintel, Intel would keep pushing Itanium and sort out the design issues. The thing with AMD64 is that now there is this myth that there was no other alternative than keeping up with x86, and Itanium redesigns for some magical reason were impossible. Other than those redesigns never happened, because AMD64 made economic invalid to pursue them.
        thequux 1mo ago
        Itanium has well over a kilobyte of general-purpose registers. That's lovely for single-process performance, but it absolutely slaughtered context switch time given the available memory bandwidth at the time. On top of that, it was fiendishly difficult to actually find instructions that could fill the instruction stream, and thus i-cache utilization was a disaster. On top of all of that, it exposed far too much microarchitecture to userspace: it would forever be pinned to having three execution ports with very specific capabilities, and any changes to the µarch would have resulted in all of the complicated register rename and instruction scheduling hardware that VLIW was supposed to avoid. I'll grant that it seemed like a decent idea at the time, but there was enough risk there that I can only describe Intel's all-in stance on Itanium to have been a blunder. (There's a worthwhile distinction to be made between a blunder and a mistake. Mistakes are calculated risks that don't pan out, whereas a blunders is something that should have been obvious that it would go poorly when the decision was made. Losing your savings in the stock market from a surprise dip is a mistake. Losing your savings by betting it all on 14 in Vegas is a blunder. Similarly, the design of Itanium was a mistake. Betting the company on it was a blunder.)

From back when IA-64 (A.K.A. Itanium) was supposed to take Intel to the promised land.

pjmlp 1mo ago

Without AMD, maybe it would have.

shdwslrkr 1mo ago
No, it wouldn't have. Without AMD rescuing x86, PowerPC wouldn't have died. MIPS wouldn't have died, and faces with the need to brake the 4Gn barrier on consumer equipment microsoft would have had windows running on three or four competing architectures until 2013 when everything would have switched to ARM. Itanium would have already been a rotting corpse. AMD rescued Intel from its own management.
- pjmlp 1mo ago
  Sure it would, Windows XP 64 bits was alreary on Itanium, and NT versions for PowerPC and MIPS were already dead by then.
  - shdwslrkr 1mo ago
    First thank you for generously understanding my post despite the vandalism that autocorrect did to it. WindowsNT is remarkably well suited to porting to other arch. This was done on purpose to hedge against x86. Dead one day, reactivated the other. MS needed to brake the 4Gb barrier and they would have done anything to get consumer priced 64bit chips. Itanium was a dog. We had an Itanium SGI "supercomputer". Everything about it that SGI designed was amazing (hot swapping cpus). The cpu was a dog.
    - pjmlp 1mo ago
      Itanium wasn't set in stone, a few times CPUs were redesigned to fix architecture issues, naturally for WinIntel that became economic unfeasible the moment AMD64 became an alternative. Without it, Intel would most likely kept iterating and improving Itanium's architecture.
  - hedgehog 1mo ago
    It's unclear to me what would have likely happened had AMD stayed on IA32 and Netburst been uncontested. Itanium was far too expensive for consumer machines and it seems very possible that Intel would have fumbled IA64 in a way similar to more recent AVX-512 and their big.little efforts. Easy enough to port XP to Itanium, hard to get those machines into Best Buy or the Dell catalog in any way that makes sense. Had AMD continued Athlon performance improvements and Intel still responded with a P6-derived Pentium M (which even in our timeline was 32-bit) it still seems like there would have been no volume market for IA64 and we still would have eventually ended up with an evolution of IA32 even if it came from Intel instead of AMD.
    - pjmlp 1mo ago
      It is all what ifs by now, however I firmly believe if there was no other option other than Wintel, Intel would keep pushing Itanium and sort out the design issues. The thing with AMD64 is that now there is this myth that there was no other alternative than keeping up with x86, and Itanium redesigns for some magical reason were impossible. Other than those redesigns never happened, because AMD64 made economic invalid to pursue them.
      - thequux 1mo ago
        Itanium has well over a kilobyte of general-purpose registers. That's lovely for single-process performance, but it absolutely slaughtered context switch time given the available memory bandwidth at the time. On top of that, it was fiendishly difficult to actually find instructions that could fill the instruction stream, and thus i-cache utilization was a disaster. On top of all of that, it exposed far too much microarchitecture to userspace: it would forever be pinned to having three execution ports with very specific capabilities, and any changes to the µarch would have resulted in all of the complicated register rename and instruction scheduling hardware that VLIW was supposed to avoid. I'll grant that it seemed like a decent idea at the time, but there was enough risk there that I can only describe Intel's all-in stance on Itanium to have been a blunder. (There's a worthwhile distinction to be made between a blunder and a mistake. Mistakes are calculated risks that don't pan out, whereas a blunders is something that should have been obvious that it would go poorly when the decision was made. Losing your savings in the stock market from a surprise dip is a mistake. Losing your savings by betting it all on 14 in Vegas is a blunder. Similarly, the design of Itanium was a mistake. Betting the company on it was a blunder.)