Honestly I thought they ditched the itanic a decade ago.
Intel to Discontinue Itanium 9700 ‘Kittson’ Processor, the Last of the Itaniums
191–200 of 211 posts
Re: Intel to Discontinue Itanium 9700 ‘Kittson’ Processor, the Last of the Itaniums
#192Earlier quoted context omitted.
> Maybe a new (or old) language will be more amenable to VLIW compilation than C? I would say certainly, given Fran Allen's point of view on C compilers.
A workflow I'd like to see: you write your code and ensure that it is functionally correct, all the tests pass. Then you go home and overnight, some ML/DL/NN whatever tool works on your code to find the best way to compile it (fastest binary that passes all tests). Repeat this every day for the duration of the project. At the end your artifacts are the source code, the shippable binary, and a model perfectly trained…
If you don't have any idea how to solve your hard problem, just claim that magic exists and call this magic Machine Learning/Deep Learning/Neural Network to make it sound more scientific.
Re: Intel to Discontinue Itanium 9700 ‘Kittson’ Processor, the Last of the Itaniums
#193Earlier quoted context omitted.
Most of it depended on the problem: for a subset of problems it worked well but once you had branchy code and less than very consistent memory access it was dismal. I supported a computational science group during that period and Itanium (and Cell) kept being tested but never made sense since you’d be looking at person-years of work hoping you could beat the current systems (or even previous generation) instead of sp…
> for a subset of problems it worked well but once you had branchy code and less than very consistent memory access it was dismal. So, a lot like coding for the GPU. Makes sense, given that the low-level architecture is so similar... And it might explain why VLIW itself is not so widely used anymore. AIUI, even the Mill proposed architecture (which boils down to VLIW + lots of tricks to cheaply improve performance on…
The GPU comparison is common and I think it hits the main problem: Intel/HP needed to solve two hard problems to succeed. GPU computing had only one because gamers provided a reliable market for the chips in the meantime.
I’m also curious how this could have gone a generation later: Itanium performance was critically dependent on compilers in an era where they were expensive and every vendor made their own, and the open source movement was just taking off. It seems like things could have gone much better if that’d been, say, LLVM backend & tools and higher level libraries where someone could get updates without licensing costs and wouldn’t be in the common 90s situation of needing to choose between the faster compiler and the more correct one.
Re: Intel to Discontinue Itanium 9700 ‘Kittson’ Processor, the Last of the Itaniums
#194Earlier quoted context omitted.
You're right, it is kind of disappointing. I think the fact that it would cost so much to come up with something novel and then optimise it to the point that conventional CPUs are at that it seems hardly worth the expenditure. The next major frontier in CPU design would appear to be in materials and manufacturing rather than architecture - although no doubt whatever the post-silicon world looks like will influence fu…
Although the possibilities are arguably greater for new designs to get traction today. There are a lot of reasons. Open source, cloud providers, etc. But a big one is that you can't just depend on CMOS process shrinks to make processors faster. Therefore, your new design isn't necessarily going to be eclipsed by whatever new x86 CPU comes out in 12 months.
That's true, but the difficulty is it's not just going to take 12 months to do something like this. A radically new architecture would take years to become competitive with today's processors for all of the use cases that would make it marketable. Meanwhile the x86 guys aren't just going to sit still, there's almost certainly more IPC to squeeze and they can add fixed function hardware (as they've already done for video encoding/decoding) or FPGA area in new product ranges and keep building new markets that way.
Re: Intel to Discontinue Itanium 9700 ‘Kittson’ Processor, the Last of the Itaniums
#195Earlier quoted context omitted.
>most of these are just past crimes^W^Wlegacy This is completely off topic, but I've seen things like the "^W^W" a few times before, and I don't know what it means. Is this a weird encoding mismatch thing? is it from some editor/system that people instinctively type? Is it from some other forum which has a strange markup syntax for something?
"^W" is this guy: https://en.wikipedia.org/wiki/End-of-Transmission-Block_char... In Unix line editors it is traditionally used to mean 'erase the previous word'. See also documentation for ASCII ( http://www.robelle.com/smugbook/ascii.html for example) for origins of ^C, ^D, ^S, etc.
As an HP3000 programmer I still refer to this link fairly often. Ah MPE, its a strange one.
Re: Intel to Discontinue Itanium 9700 ‘Kittson’ Processor, the Last of the Itaniums
#196Earlier quoted context omitted.
There's MIPS as well out there, which is being opened up: https://wavecomp.ai/mipsopen Not sure it presents much of an advantage over any of the existing architectures, or RISC-V, though.
MIPS today isn't what it used to be. It mostly occupies the "we're too cheap to use ARM" segment of the market these days, which is an ignominious fate for what used to be a great architecture. But it's well known and it still has its wonderful instruction set, so maybe someone can make it shine again once it goes fully open.
The few times I've dealt with MIPS architecture, it has seemed like software isn't really that well optimised for it. It works. Just... not as fast as it can do, e.g. zlib.
There are some forked versions of the main zlib library with MIPS optimisations in them that really fly, but nothing that has ever hit upstream, and I'm not crazy enough to want to rely on unpatched/unsupported code like that.
Re: Intel to Discontinue Itanium 9700 ‘Kittson’ Processor, the Last of the Itaniums
#197Earlier quoted context omitted.
PA-RISC was my favorite from that time. If it had the software stack of Sun commercial Unix might still be a thing.
I don't know a lot about PA-RISC, can you what was it about that ISA differentiated it?
It didn’t get hung up on RISC purity and introduced a series of instructions that kept code sizes down: single instruction Indexed Loads (normal and scaled), single instruction Address updates, bitfield operations, FMADD, subword operations (making decimal math ops faster), a bunch of branch path instructions and a handfull of others.
It had 32 64bit FP registers that could also be used as 64 32bit registers or 16 128bit registers. For the time this was novel.
Re: Intel to Discontinue Itanium 9700 ‘Kittson’ Processor, the Last of the Itaniums
#198Earlier quoted context omitted.
> They shouldn't have killed an excellent processor (the Alpha) Parallel Alpha systems are a pain to deal with, because they lack a form of expected synchronization that every other processor has: automatic data dependency barriers. On every other platform, if you initialize or otherwise write to a value, then make a pointer point to that value, you can expect that anyone reading through that pointer gets the initial…
Had alpha not died, they could have tightened the memory model.
At the expense of the great performance.
Re: Intel to Discontinue Itanium 9700 ‘Kittson’ Processor, the Last of the Itaniums
#199Earlier quoted context omitted.
True, my point is that itanium itself was a laughingstock, and clearly with no future, so must have been embarrassing to talk to your friends about what you do for work. Making spare parts for the B-52, or maintaining security fixes for Solaris (which has its fanatic fans) can be rewarding, no question. But to work on the Itanium any time in the last decade must have been soul-sucking.
I was an HP-UX kernel engineer from 2002 til 2005, a brief interlude writing IA64 CPU diagnostics, and then and a Linux kernel engineer from 2007 til 2010, all on Itanium systems. In that time frame, it wasn't clear that horizontal scale out architecture (aka "the cloud") was going to dominate, and that scale up systems were going the way of the mainframe. The thinking was that there would always be a healthy balance…
thanks.
Re: Intel to Discontinue Itanium 9700 ‘Kittson’ Processor, the Last of the Itaniums
#200Earlier quoted context omitted.
Had alpha not died, they could have tightened the memory model.
At the expense of the great performance.
Is there any evidence that not handling read-read dependencies in hw is crucial to alpha performance?
I'd guess that back when the alpha memory model was designed multiprocessors were quite rare, and designers didn't have such a clear picture of the tradeoffs that we do today (not saying today's understanding is perfect, just that it's better than what we had 30 years ago), and chose the weakest possible model they could come up with in order to not constrain future designers.