- There is an open bug to adjust the simd sort behavior on AMD zen 4 cores due
to poor performance of an AVX 512 instruction. The simplest solution is to fall
back to AVX2. That may be simpler to manage in Java? (I was looking at the
HotSpot code).
For now, the patch guards AVX512 entries with VM.isIntelCPU() check. In order
to distinguish between AMD Zen 4 and 5, either a new platform-sensing check is
needed or reimplementation of x86-specific platform sensing in Java on top of
CPUID info.
Probably best just to update as required. (Also I don’t seem anything in the
HotSpot code to determine the AMD zen core version.)
Yes, it's not implemented yet. But there are enough examples for Intel
chips to see how it will look like (e.g., is_intel_skylake() or
is_knights_family()).
Any general CPU vendor/model solution seems a little more challenging than that
of surfacing up the CPU feature set as a string. Note that the
System.getProperties() surfaces up “os.arch”. A more general solution could add
further properties for the CPU?
Personally, I'm not a fan of "stringy" APIs. It may look convenient at
first, but it suffers from deficiencies of both approaches. I would
prefer to use a strongly typed platform-specific API instead (an
equivalent of VM_Version class in hotspot).
Best regards,
Vladimir Ivanov
