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Intel is removing AVX-512 support from their newer CPU's (Alder Lake +). :/ https://www.igorslab.de/en/intel-deactivated-avx-512-on-alder-lake-but-fully-questi

Intel is removing AVX-512 support from their newer CPU's (Alder Lake +). :/ https://www.igorslab.de/en/intel-deactivated-avx-512-on-alder-lake-but-fully-questionable-interpretation-of-efficiency-news-editorial/ https://www.igorslab.de/en/intel-deactivated-avx-512-on-alde...

mhh__ 4y ago
You're forgetting about server CPUs, and we don't know yet about Raptor Lake.
- Andoryuuta 4y ago
  Ah, yep. You're totally right. I didn't even consider server CPUs. Also, I thought I read somewhere that it was for all consumer CPUs starting at Alder Lake, but I have no idea where, so I could be entirely wrong. :)
SemanticStrengh 4y ago
And zen 4 is rumoured to add support for it ^^
electricshampo1 4y ago
This is only on the client side; server still has and will have AVX512 for the foreseeable future.
PragmaticPulp 4y ago
Server and workstation chips still have AVX-512. It’s only unsupported on CPUs with smaller E(fficeincy) cores. AVX-512 was never really supported in newer consumer CPUs with heterogeneous architecture. These CPUs have a mix of powerful cores and efficiency cores. The AVX-512 instructions were never added to the efficiency cores because it would use way too much die space and defeat the purpose of efficiency cores. There was previously a hidden option to disable the efficiency cores and enable AVX-512 on the remaining power cores, but the number of workloads that would warrant turning off a lot of your cores to speed up AVX-512 calculations is virtually non-existent in the consumer world (where these cheap CPUs are targeted). The whole journalism controversy around AVX-512 has been a bit of a joke because many of the same journalists tried to generate controversy when AVX-512 was first introduced and they realized that AVX-512 code would reduce the CPU clock speed. There were numerous articles about turning off AVX-512 on previous generation CPUs to avoid this downclocking and to make overclocks more stable.
- R0b0t1 4y ago
  That's not a valid reason why I can't use them on the P cores. Some motherboards can enable them on the i9-12900k, it works fine, but you need to pin to a P core.
  - PragmaticPulp 4y ago
    The reason is that it was never validated or tested with AVX-512 and Intel and motherboard vendors couldn’t commit to shipping everything with AVX-512 support in future steppings/revisions. If you disable E cores you could enable AVX-512 on certain motherboards, but like I said that’s not really a net win 99.99% of the time when you’re giving up entire cores. It was also at your own risk because presumably the power/clock speed profiles were never tuned for a feature that wasn’t actually supported. I can see exactly why they turned it off on newer CPUs only after an announcement.
    - R0b0t1 4y ago
      Still smells like bullshit. Let the customer decide. Who cares if it was validated? Why was it even included? Just put it behind a yes-I-really-mean-it-switch so nobody uses it by accident.
      - kadoban 4y ago
        There's not many great places for such a switch, and even then, then you have to validate _that_ behavior. It's mostly just not worth it.
        pantalaimon 4y ago
        Several motherboard vendors added that very switch in UEFI (some even with the option to force an older microcode version AFAIK) before it was disabled in hardware by Intel
    - Dylan16807 4y ago
      > it was never validated or tested with AVX-512 and Intel and motherboard vendors couldn’t commit Only because they screwed it up on purpose! That's not an acceptable reason for removing the feature; in part because it would apply to any feature they decided to cut.

mhh__ 4y ago

You're forgetting about server CPUs, and we don't know yet about Raptor Lake.

Andoryuuta 4y ago
Ah, yep. You're totally right. I didn't even consider server CPUs. Also, I thought I read somewhere that it was for all consumer CPUs starting at Alder Lake, but I have no idea where, so I could be entirely wrong. :)

SemanticStrengh 4y ago

And zen 4 is rumoured to add support for it ^^

electricshampo1 4y ago

This is only on the client side; server still has and will have AVX512 for the foreseeable future.

PragmaticPulp 4y ago

Server and workstation chips still have AVX-512. It’s only unsupported on CPUs with smaller E(fficeincy) cores. AVX-512 was never really supported in newer consumer CPUs with heterogeneous architecture. These CPUs have a mix of powerful cores and efficiency cores. The AVX-512 instructions were never added to the efficiency cores because it would use way too much die space and defeat the purpose of efficiency cores. There was previously a hidden option to disable the efficiency cores and enable AVX-512 on the remaining power cores, but the number of workloads that would warrant turning off a lot of your cores to speed up AVX-512 calculations is virtually non-existent in the consumer world (where these cheap CPUs are targeted). The whole journalism controversy around AVX-512 has been a bit of a joke because many of the same journalists tried to generate controversy when AVX-512 was first introduced and they realized that AVX-512 code would reduce the CPU clock speed. There were numerous articles about turning off AVX-512 on previous generation CPUs to avoid this downclocking and to make overclocks more stable.

R0b0t1 4y ago
That's not a valid reason why I can't use them on the P cores. Some motherboards can enable them on the i9-12900k, it works fine, but you need to pin to a P core.
- PragmaticPulp 4y ago
  The reason is that it was never validated or tested with AVX-512 and Intel and motherboard vendors couldn’t commit to shipping everything with AVX-512 support in future steppings/revisions. If you disable E cores you could enable AVX-512 on certain motherboards, but like I said that’s not really a net win 99.99% of the time when you’re giving up entire cores. It was also at your own risk because presumably the power/clock speed profiles were never tuned for a feature that wasn’t actually supported. I can see exactly why they turned it off on newer CPUs only after an announcement.
  - R0b0t1 4y ago
    Still smells like bullshit. Let the customer decide. Who cares if it was validated? Why was it even included? Just put it behind a yes-I-really-mean-it-switch so nobody uses it by accident.
    - kadoban 4y ago
      There's not many great places for such a switch, and even then, then you have to validate _that_ behavior. It's mostly just not worth it.
      - pantalaimon 4y ago
        Several motherboard vendors added that very switch in UEFI (some even with the option to force an older microcode version AFAIK) before it was disabled in hardware by Intel
  - Dylan16807 4y ago
    > it was never validated or tested with AVX-512 and Intel and motherboard vendors couldn’t commit Only because they screwed it up on purpose! That's not an acceptable reason for removing the feature; in part because it would apply to any feature they decided to cut.