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Intel completely disables AVX-512 on Alder Lake after all

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Re: Intel completely disables AVX-512 on Alder Lake after all

#151

Post by loup-vaillant »

salawat wrote: post #137
Fnoord wrote: post #111

Earlier quoted context omitted.

Lets compare it to all the other options, shall we? Perfect is the enemy of good, and your uncompromising way of doing things (including not loading microcode 'because it is closed source') is, to put it simple: harmful. And unusual, as well (its not a dealbreaker for many people). The laptop is modular and repairable, just like a Fairphone is modular and repairable. Its a great step forward and, while not perfect an…

...I'm more curious why firmware is even closed source. Seems to me, just releasing the assembler, documentation and a datasheet should be basic courtesy. Then again everything I think that way about is apparently a mortal sin in the business world.

I hear hardware vendors are scared shitless of running awful of other hardware vendor's patents. If they released their firmware, this would give other folks ammunitions to attack them in court.

Personally, I don't care much about firmware being proprietary, if it cannot be used to meaningfully change the functionality of the chip. But I do care about the chip ultimately following a public specification. I want an ISA just like x86, ARM, or RISC-V. Tell me the size and format of the ring buffer I must write to or read from, and I'll program the rest.

But even that is still too much to ask for apparently. Graphics cards are getting closer with lower level drivers like DX12 and Vulkan, but we're not quite there yet.

Re: Intel completely disables AVX-512 on Alder Lake after all

#152

Post by fsflover »

Fnoord wrote: post #111
fsflover wrote: post #69

Earlier quoted context omitted.

> AMD Ryzen Framework laptop would be amazing Except you cannot disable AMD PSP.

Lets compare it to all the other options, shall we? Perfect is the enemy of good, and your uncompromising way of doing things (including not loading microcode 'because it is closed source') is, to put it simple: harmful. And unusual, as well (its not a dealbreaker for many people). The laptop is modular and repairable, just like a Fairphone is modular and repairable. Its a great step forward and, while not perfect an…

> your uncompromising way of doing things (including not loading microcode 'because it is closed source')

Libreboot disagrees with that: https://lists.gnu.org/archive/html/libreplanet-discuss/2022-....

Also, FSF would never endorse an Intel CPU with disabled Intel ME. It must be fully removed to get the RYF certification.

Re: Intel completely disables AVX-512 on Alder Lake after all

#153

Post by xondono »

mhh__ wrote: post #125
_xnmw wrote: post #41

Between shenanigans like this and Spectre/Meltdown mitigations giving me a ~20% performance hit [1], I avoid Intel like the plague if I have the choice. [1] https://arxiv.org/pdf/1807.08703.pdf

Pretty crap reasoning then. Intel never ever marketed these as having AVX-512 and unless you are running a Xeon from 2012 like the paper you've linked a modern CPU (note, any desktop class CPU) will only be vulnerable to some bits of Spectre and not meltdow

My 7700K (2017) got a similar downgrade in performance from the mitigations.

Switched to AMD for the first time in my life, no regrets so far.

Re: Intel completely disables AVX-512 on Alder Lake after all

#154

Post by tjoff »

codeflo wrote: post #11

If all of this was planned (and I’m not saying it is), that would have been very clever. It would work like this: 1. You “accidentally forget” to disable the feature in hardware. Given how competitive the market is, motherboard manufacturers can be relied upon to enable it in their “1337 OVERCLOCKZ” mode. No conspiracy is needed. 2. You “tolerate” this practice just long enough to win the critical initial wave of rev…

* 1. Very few “evil schemes” exist in reality because people aren’t all that clever (and all that evil)*

Uh, no. That is a very common technique commonly used the last 15 years.

Many products have different parts, such as different types for display panels in different revisions. So a very common tactic is to only release the one with the superior part at first.

And a few weeks/months later all the reviews have been written or at least have sourced their review sample you start pushing the cheaper version.

Mobile phones, computer displays, TVs etc. suffer from this. Perhaps less so nowadays because most of those critical components are specified in the spec. sheet.

Re: Intel completely disables AVX-512 on Alder Lake after all

#155

Post by marcan_42 »

vanderZwan wrote: post #129
marcan_42 wrote: post #96

Earlier quoted context omitted.

Yup. PCIe will practically run over wet string, thanks to error detection and retransmits and other reasons, but try having a marginal DRAM bus and see how much fun that is...

Could be a fun way to test and demonstrate robustness of various parts of computer hardware, actually. It's already been done with ADSL for example: [0] https://www.revk.uk/2017/12/its-official-adsl-works-over-wet...

My comment was actually a self quote from a talk I gave about PS4 hacking where I described that PCIe will happily run over bare soldered wires without much care for signal integrity, at least over short distances (unlike what you might expect of a high-speed bus like that) :)

Not literally wet string, but definitely low tech. ADSL is special though, not many technologies can literally run over wet string :-)

Re: Intel completely disables AVX-512 on Alder Lake after all

#156

Post by cameron_b »

vanderZwan wrote: post #129
marcan_42 wrote: post #96

Earlier quoted context omitted.

Yup. PCIe will practically run over wet string, thanks to error detection and retransmits and other reasons, but try having a marginal DRAM bus and see how much fun that is...

Could be a fun way to test and demonstrate robustness of various parts of computer hardware, actually. It's already been done with ADSL for example: [0] https://www.revk.uk/2017/12/its-official-adsl-works-over-wet...

off topic, but I commend the article if just for the conclusion

Re: Intel completely disables AVX-512 on Alder Lake after all

#157

Post by gambiting »

josephcsible wrote: post #138
gambiting wrote: post #7

Earlier quoted context omitted.

It was never advertised, and Intel very specifically said AVX-512 instructions will not be available. Some motherboard manufacturers made them available anyway, now Intel is fixing that. It's like buying a car with an advertised speed limiter of 155mph, then finding that actually it can go 170mph, and then the manufacturer fixes the speed limiter with a software update. Yes we know the car could go faster, but the sp…

This has nothing to do with advertisement. You should not be able to retroactively make products that you've already sold to people be less useful, whether or not the feature you're clawing back was advertised.

I disagree completely. The product as sold wasn't compliant with its own technical spec sheet - now after the update it is. The feature isn't supported by that CPU and it should have never been exposed to the consumer. If you discovered that the CPU has 8 cores despite being sold as a 6 core, then removing 2 cores with a BIOS update wouldn't be "making the product less useful" either. It just makes the product exactly as specified in its technical documentation - and that is how it should be.

Let me play a devil's advocate here - what if using the feature actually damages the processor after a while? AVX instructions always generate a tonne of heat. Maybe that's the reason why it was meant to be unsupported in the first place. Should Intel be allowed to fix the CPU and bring it in line with spec, or is that "making the product less useful"?

Edit: also - Intel isn't forcing anyone to install this BIOS update. If you want to keep it with AVX instructions available, at the cost of disabling all efficiency cores - sure, keep it that way.

Re: Intel completely disables AVX-512 on Alder Lake after all

#158

Post by tymscar »

MikeKusold wrote: post #142
tymscar wrote: post #122

Earlier quoted context omitted.

Not anymore! Nvidia gpus can be passed through just fine with no fixes. I use mine like that daily

Are you doing a full pass through or vGPU?

Full pass through. Been doing it for years. I have a youtube video on how I did it on my channel. Same username

Re: Intel completely disables AVX-512 on Alder Lake after all

#159

Post by gambiting »

Someone wrote: post #148
jacquesm wrote: post #27

Earlier quoted context omitted.

Yes, but once it has shipped and people may have come to depend on it it will break stuff, not fix stuff. Besides the obvious benefit of first having benchmarks out there claiming these chips are better than they really are. So this change just benefits Intel, and nobody else. If it would be a fix then it would be that something that was advertised did not work, and now it does.

> Yes, but once it has shipped and people may have come to depend on it it will break stuff, not fix stuff. That may apply to every change, including things everybody agrees on to be bug fixes. If, for example, you improve the number of correctly returned bits for computing sin , that can break programs, for example games that want to keep world models in exact sync across systems. From what I read here, intel didn’t…

To add to this - even if the motherboard manufacturer allows this despite Intel's advice, in their stock configuration none of those CPUs allow AVX-512 instructions out of the box. You need to knowingly and conciously go into the BIOS and disable all efficiency cores first, to make this option even appear. So "as sold" the product doesn't support AVX-512 instructions and the advertising is absolutely correct. Just like you can overclock the CPU but it doesn't come overclocked out of the box(and Intel assumes no liability if you do overclock it).

Re: Intel completely disables AVX-512 on Alder Lake after all

#160

Post by yjftsjthsd-h »

im3w1l wrote: post #132
PragmaticPulp wrote: post #86

Earlier quoted context omitted.

> 2. You “tolerate” this practice just long enough to win the critical initial wave of reviews and benchmarks. Interested buyers will look at those charts for years to come. That’s not what happened here. The AVX-512 instructions not only weren’t enabled by default, they couldn’t be enabled at all unless you went out of your way to disable the efficiency cores completely. They also wouldn’t benefit your workload unle…

Comparing the facts to all the suspicious people here, it made me realize something. Our zeitgeist sure is a cynical one.

Intel has spent decades accumulating its reputation. Sometimes cynicism is appropriate.
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