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A new Intel Itanium (IA-64) emulator that boots Windows

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Re: A new Intel Itanium (IA-64) emulator that boots Windows

#31

Post by wmf »

ColdStream wrote: post #23
Joel_Mckay wrote: post #14

Earlier quoted context omitted.

To be fair, most of ia64 performance issues were in the more complicated compilers. The chip itself had potential, but essentially abandoned the DOS/Windows market inertia. =3

Itanium is yet another example of how difficult it is to fight software ecosystem momentum. It had potential but until you have an easy transition path, few will consider it. Apple figured that out during the 68K > PPC > X86 > ARM transitions.

Itanium 1 had hardware x86 compatibility and Itanium 2 had software x86 emulation just like Apple. It wasn't enough.

Re: A new Intel Itanium (IA-64) emulator that boots Windows

#32

Post by kstrauser »

Joel_Mckay wrote: post #28
qubex wrote: post #16

Earlier quoted context omitted.

Yeah EPIC pushed too much effort onto compilers and removed the context awareness of out of order reordering etc and the result was just a lame duck.

[flagged]

You've mentioned Intel's compilers a few times but they're not a magic thing that could make Itanic not-suck. Suppose they make general purpose code that's twice as fast as GCC when the whole computer is dedicated to running one specific process. They don't, but let's pretend. Even in that ideal scenario, it falls apart as soon as you're processing unpredictable input. VLIW sucks hard at chewing through data that's not precisely what it's expecting. You could probably make a video codec that performed really well, but it would be impossible to make a database that performed consistently not-badly. It's not that the existing compilers weren't good enough, not even the magic Intel ones. It's that it's not possible to pre-generate VLIW opcodes that do well when the input value isn't a homogeneous stream. Even if Intel's code was 2x better than GCC's — and again, it wasn't — twice abominable was still abominable.

I wasted more time SSHed into an Itanic than most people had to, so I'm speaking from first-hand experience. Some very, very specific Itanium code was a bit faster than the equivalent x86 or similar. That was always some very tightly scoped thing that did the exact same tight loop a gazillion times, like en-/decrypting a data stream. Anything more heterogenous ran poorly, as in multiple times the wall-clock time of the same workload on the x86 server next to it that cost a tenth as much. And that's even when using the magic Intel compilers.

Itanium was bad. The compiler tech didn't exist to make it not-bad, and in retrospect I think it become obvious that it couldn't exist. It wasn't a matter of the compiler authors needing to be clever. It was more like making Itanium live up to the hype required making P=NP.

Re: A new Intel Itanium (IA-64) emulator that boots Windows

#33

Post by kstrauser »

lorreyfum wrote: post #15

The Itanic was built specifically by HP to sink Fujitsu, hitachi, nec, unisys and sgi. So in that sense it was a success.

This was my take on it: https://honeypot.net/2021/07/29/the-itanic-has.html

Key relevant quote:

> In 1994, Intel and HP looked around and saw a wide variety of successful server CPU architectures like Alpha, MIPS, SPARC, and POWER. This annoyed them and they decided to make a new CPU that no one would want to use.

Re: A new Intel Itanium (IA-64) emulator that boots Windows

#36

Post by MBCook »

wmf wrote: post #31
ColdStream wrote: post #23

Earlier quoted context omitted.

Itanium is yet another example of how difficult it is to fight software ecosystem momentum. It had potential but until you have an easy transition path, few will consider it. Apple figured that out during the 68K > PPC > X86 > ARM transitions.

Itanium 1 had hardware x86 compatibility and Itanium 2 had software x86 emulation just like Apple. It wasn't enough.

Right.

PPC was significantly faster than m68k. Intel was significantly faster again. Finally ARM was yet again.

(ARM and Intel especially on laptops)

They could pay the emulation price and still come out equal or usually on top. Even when equal there were often other benefits, like reduced heat.

As I remember hearing Itanium was a dog with x86 code. It never got fast enough to compete let alone supplant it during emulation right?

So it wasn’t (meaningfully?) faster on recompiled code or new code. It wasn’t faster on new code. But it cost way more.

Not a winning combination.

Re: A new Intel Itanium (IA-64) emulator that boots Windows

#37

Post by MBCook »

Joel_Mckay wrote: post #27
ColdStream wrote: post #23

Earlier quoted context omitted.

Itanium is yet another example of how difficult it is to fight software ecosystem momentum. It had potential but until you have an easy transition path, few will consider it. Apple figured that out during the 68K > PPC > X86 > ARM transitions.

Agreed, everyone has a pet architecture that fascinates them, but if its so good only 5 people can code for the target... it is e-waste within a year. Apple is an exception as it has always had a walled-garden ecosystem with the OS, so can force shifts in architectures unlike most companies. The M3/M4 Pro series with unified GPUs is probably the best design on the consumer market right now, but people are not leverag…

The walled garden is an advantage of some sort, but they’ve also never made a bad call on switching architectures.

We don’t know what it would look like if Apple had chosen something that ended up like Itanium. It’s quite possible they don’t have the clout to pull it off.

(Maybe they should have gone Intel instead of PPC, but both were significantly better than m68k at that point)

Re: A new Intel Itanium (IA-64) emulator that boots Windows

#38

Post by MBCook »

monster_truck wrote: post #29
userbinator wrote: post #3

Earlier quoted context omitted.

It's interesting to see how LLMs have definitely become a force-multiplier to motivate people into doing things they wouldn't otherwise have the time and effort to.

In this domain and others like it especially! It's bone crushingly dry to try and figure this kind of shit out yourself, can do everything right according to every available reference and code comment only to get compiler and linker errors nobody has ever seen or posted about. Weeks and weeks of smashing your face against a wall until it gives. Now anyone can get twice as far in an evening. And that fuckin rules Hard…

Plus you can point it at actual software or tests with known results and tell it to keep going until it gets it.

Re: A new Intel Itanium (IA-64) emulator that boots Windows

#39

Post by Joel_Mckay »

kstrauser wrote: post #32
Joel_Mckay wrote: post #28

Earlier quoted context omitted.

[flagged]

You've mentioned Intel's compilers a few times but they're not a magic thing that could make Itanic not-suck. Suppose they make general purpose code that's twice as fast as GCC when the whole computer is dedicated to running one specific process. They don't, but let's pretend. Even in that ideal scenario, it falls apart as soon as you're processing unpredictable input. VLIW sucks hard at chewing through data that's n…

My point was most modern software developers still do not understand systems at an architectural level. I don't buy the VLIW paradigm was inherently inferior argument, but the code written for it with mystery failure modes at the time was a mess.

And ia64 was only around 23% slower and several times more costly than amd64 options at the time. Both toads had their warts, but one was actually usable by mere mortals.

Its true just about everything either ran slow on not at all on ia64... Thankfully, we were still running Sparc based platforms at that time, as the Intel clown-show still looked like more work. But I do empathize with the ia64 trauma, as the roll out had a lot of collateral damage in some firms as people started jumping ship early to avoid accountability. =3

Re: A new Intel Itanium (IA-64) emulator that boots Windows

#40

Post by speed_spread »

butterisgood wrote: post #17

When it comes to Itanium all I can think of is how I wish I could have an Alpha. And how no one should care about Itanium. It’s the product of companies bent on doing all the wrong things.

Alpha was great but that wasn't enough against the convenience of just running an x86 box. It didn't find a niche quickly enough. ARM survived because they were low power. POWER survived because IBM is one big niche. MIPS died and reincarnated into RISC-V. I have no idea where Alpha would have gone had it not been dropped.
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