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Intel and AMD form advisory group to reshape x86 ISA

theregister.com

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Re: Intel and AMD form advisory group to reshape x86 ISA

#61

Post by Twirrim »

sedatk wrote: post #39

After 40+ years, finally :) I really want x86 and ARM to push each other for better power efficiency and performance instead of one side winning out. I’m using an ARM laptop nowadays and the battery life is so impressive.

I've been surprised by the lack of polish in Golang for Arm, given all major clouds have server class, high performance, Arm processors, and Google even has their own. There's stuff on their backlog that is still unaddressed around the code generation, and if you compare the output in Godbolt, you can see the inefficiencies.

Re: Intel and AMD form advisory group to reshape x86 ISA

#62

Post by emn13 »

Remnant44 wrote: post #37

This is hopeful. Whatever the ARM enthusiasts would like, x86 is going to stick around for a long time, and working together to evolve the ISA extensions in a more cohesive manner would go a long way. In particular, I'd really like AMD and Intel to get on the same page in terms of avx10 / avx512 support. Many people correctly note that avx512 support is not super relevant today, but this can be laid heavily at the fe…

Phoronix has a specific benchmark subset that tries to tease out (at least for zen5) a hint of how much the wider data-path matters vs. how much the frontend/ISA extension itself, by disabling those selectively on an epyc zen5 chip: https://www.phoronix.com/review/amd-epyc-9755-avx512

It's pretty clear that the ISA/frontend is much more impactful than the data-width on this set of workloads, and that also seems to jive with more indirect evidence from performance patterns more broadly.

i.e. it's the new instructions (and potentially register width) that matter significantly more than the actually wider data-path.

Re: Intel and AMD form advisory group to reshape x86 ISA

#63

Post by ChuckMcM »

Feels like one of the signs of the apocalypse :-) And it is a pretty stunning "conclusion" to a war that started 20 years ago with the introduction of Sledgehammer and the AMD64 instruction set.

For me though it really emphasizes how much of a threat ARM (and presumably RISCV) architectures are to these two companies.

Re: Intel and AMD form advisory group to reshape x86 ISA

#64

Post by emn13 »

hggigg wrote: post #56
pizza234 wrote: post #46

Earlier quoted context omitted.

Very surprisingly, x86 can be competitive (and in some cases, even winning) in terms of power efficiency; see https://www.phoronix.com/review/amd-epyc-9965-ampereone/5 .

If you compare a good x86 to a crap ARM yes. Laptops are populated mostly with crap x86 and good ARM (apart from snapdragon which is a crap ARM)

That statement strongly suggests it's the implementation of the ISA that matters more than the ISA, whether that be due to process node, skill and investment by the manufacturer, or perhaps a bit of luck.

By good ARM, do you mean specifically (and only) Apple? Given their budgets (both financial and transistor), their very long history and investment into their chips, their deep integration of stuff like memory and GPU, and their tendency to be a process node ahead of their competitors, Apple is a particularly hard example to interpret when it comes to ISA impact.

Hard to imagine another company making all those choices, since they all have costs too, which many won't be willing or able to bear, and some of those costs (like the lack of flexibility due to the deep integration) are possibly a non-starter for many niches.

Re: Intel and AMD form advisory group to reshape x86 ISA

#65

Post by tliltocatl »

Everyone is commenting on "let x86 die" and I would agree if it was just about ISA. But the problem is that x86 has some-sorta-total-disaster-of-a-standard for peripherals and configuration (ACPI, UEFI and so on) and you can actually buy a computer that is compliant and will run Linux out of the box, even if with some glitches.

ARM is a handful of totally incompatible SoCs and you are totally dependent on SoC integrator providing support (hopefully in the form of throw-over-the-fence-and-forget Linux kernel headers, but more common are just kernel binaries) to run it at all. In theory UEFI supports ARM, but can I buy a desktop ARM processor that does? And this is going to be worse with RISC-V because hardware vendor are not interested in providing platform compatibility. So we would be back in pre-PC era platform-wise.

There is no replacement for x86, not because it is impossible to replace, but because no vendor is interested in making one.

Re: Intel and AMD form advisory group to reshape x86 ISA

#66

Post by tenebrisalietum »

layer8 wrote: post #55
blackeyeblitzar wrote: post #51

Earlier quoted context omitted.

I was wondering about this as well. What do Intel and AMD gain from protecting x86? Why not just adopt RISC-V themselves and make the best processors and process for that? Wouldn’t that get them what they want (in terms of their company’s strategy)? There’s not really value in the architecture itself as much as the real products they sell, right (the actual processors)?

The value of the ISA is the huge volume of existing software for it, including hardware drivers. The whole x86-using industry migrating away from x86 would be a multi-decade and costly process. In addition, this would just mean more competition for Intel and AMD, as they would lose the moat of their x86 know-how. Why would they do that?

Nah. Not in this day and age. Most of that software can be recompiled - hopefully no one is writing stuff in assembly, at least not to the point where it can't easily be ported. With many-core CPUs cheap and common, everything is fast. Hardware drivers matter less in the 2020s - there is far less diversity of hardware than there was in the 1990s. x86 "know-how" is vendor lock-in, not a benefit.

Re: Intel and AMD form advisory group to reshape x86 ISA

#67

Post by sedatk »

emn13 wrote: post #64
hggigg wrote: post #56

Earlier quoted context omitted.

If you compare a good x86 to a crap ARM yes. Laptops are populated mostly with crap x86 and good ARM (apart from snapdragon which is a crap ARM)

That statement strongly suggests it's the implementation of the ISA that matters more than the ISA, whether that be due to process node, skill and investment by the manufacturer, or perhaps a bit of luck. By good ARM, do you mean specifically (and only) Apple? Given their budgets (both financial and transistor), their very long history and investment into their chips, their deep integration of stuff like memory and G…

I think parent means "Ampere" being a bad ARM implementation, and Snapdragon X or Apple M-series being the good ones.

It's mentioned in the article too. Ampere performs really poorly on idle (101W vs EPYC's meager 19W). I haven't witnessed that problem on my Snapdragon X laptop.

I'm not saying Ampere is bad myself though. It's obviously very competitive being a relatively new player and all. But, it's not as polished for desktop/laptop workloads as it seems.

Re: Intel and AMD form advisory group to reshape x86 ISA

#68

Post by sidewndr46 »

tliltocatl wrote: post #65

Everyone is commenting on "let x86 die" and I would agree if it was just about ISA. But the problem is that x86 has some-sorta-total-disaster-of-a-standard for peripherals and configuration (ACPI, UEFI and so on) and you can actually buy a computer that is compliant and will run Linux out of the box, even if with some glitches. ARM is a handful of totally incompatible SoCs and you are totally dependent on SoC integra…

I'm pretty fearful of the death of x86 because it probably implies the death of easily accessible hardware for general purpose computing. If I go to a big box store and buy any AMD or Intel laptop I can throw whatever kernel and userspace I want on it in a few minutes. The Chromebook movement has already been working to close this off.

If x86 dies we will wind up with a bunch of devices where step 1 is "run this code to exploit a buffer overflow to bypass the locked bootloader. Only works on v1.2 PCB revision 7"

Re: Intel and AMD form advisory group to reshape x86 ISA

#69

Post by immibis »

tenebrisalietum wrote: post #66
layer8 wrote: post #55

Earlier quoted context omitted.

The value of the ISA is the huge volume of existing software for it, including hardware drivers. The whole x86-using industry migrating away from x86 would be a multi-decade and costly process. In addition, this would just mean more competition for Intel and AMD, as they would lose the moat of their x86 know-how. Why would they do that?

Nah. Not in this day and age. Most of that software can be recompiled - hopefully no one is writing stuff in assembly, at least not to the point where it can't easily be ported. With many-core CPUs cheap and common, everything is fast. Hardware drivers matter less in the 2020s - there is far less diversity of hardware than there was in the 1990s. x86 "know-how" is vendor lock-in, not a benefit.

Will you recompile the proprietary Nvidia driver for a GTX260? (not a typo)

Re: Intel and AMD form advisory group to reshape x86 ISA

#70

Post by immibis »

CamperBob2 wrote: post #45
akira2501 wrote: post #27

Earlier quoted context omitted.

No one "needs" a particular architecture. It's just that some of them are better suited to certain problems than others. If you really want to get rid of something and "move on" why not get rid of the wild class of devastating speculation bugs that every OOO processor in existence currently has? Far more valuable than worrying about how instruction bits are arranged in a stream.

why not get rid of the wild class of devastating speculation bugs that every OOO processor in existence currently has? Because almost no one but cloud-computing providers have a threat model that justifies the performance hit (and, not coincidentally, the carbon footprint) associated with crippled CPUs.

Laptops could do with the power use reduction.
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