RFR: 8360934: Add AVX-512 intrinsics for ML-KEM - enhancement on AVX512_VBMI [v4]

[Jatin Bhateja]

On Sun, 11 Jan 2026 09:31:03 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>>> Better to align loop sarting address to OptoLoopAlignment
>> 
>> For parity, should I do this for the other labels in the file as well?
>> 
>>> I will run the micro benchmark on AMD Turin and report by back early next week.
>> 
>> That would be great, thank you for doing this!
>
> Just a note on LoopAlignment, there are multiple moving parts here, first aligning starting addresses of loop to 64 ([recommendation from Zen5 optimization guide](https://docs.amd.com/v/u/en-US/58455_1.00) section 2.8.3) ensure small loop bodies are not split-across the cache line, if that happens then there is a code entry penalty since for first iteration of loop front-end will have to read multiple L1I cachelines, once its decoded and uops are part of Op-cache (AMD) or DSB (Intel) then uops stream for successive loop iterations are emitted from op-cache. Since op-cache is shared b/w 2 HW threads in SMT configuration hence in case of noisy neighbor scenarios or context-switches we may hit code-entry penalty during lifetime of loop. 
> 
> So its advisable to add alignment in this case for other labels before loops we already have OptoLoopAlignment in place.

> > Better to align loop sarting address to OptoLoopAlignment
> 
> For parity, should I do this for the other labels in the file as well?
> 
> > I will run the micro benchmark on AMD Turin and report back by early next week.
> 
> That would be great, thank you for doing this!

Here are the score on Turin.


Baseline:
Benchmark                                    (algorithm)  (keyLength)  (provider)   Mode  Cnt      Score   Error  Units
KeyPairGeneratorBench.MLKEM.generateKeyPair   ML-KEM-512            0              thrpt    2  62235.790          ops/s
KeyPairGeneratorBench.MLKEM.generateKeyPair   ML-KEM-768            0              thrpt    2  38238.390          ops/s
KeyPairGeneratorBench.MLKEM.generateKeyPair  ML-KEM-1024            0              thrpt    2  24725.512          ops/s

Withopt:
Benchmark                                    (algorithm)  (keyLength)  (provider)   Mode  Cnt      Score   Error  Units
KeyPairGeneratorBench.MLKEM.generateKeyPair   ML-KEM-512            0              thrpt    2  62483.697          ops/s
KeyPairGeneratorBench.MLKEM.generateKeyPair   ML-KEM-768            0              thrpt    2  38464.272          ops/s
KeyPairGeneratorBench.MLKEM.generateKeyPair  ML-KEM-1024            0              thrpt    2  24702.044          ops/s



Baseline:
Benchmark             (algorithm)  (provider)   Mode  Cnt      Score   Error  Units
KEMBench.decapsulate   ML-KEM-512              thrpt    2  46416.479          ops/s
KEMBench.decapsulate   ML-KEM-768              thrpt    2  28516.289          ops/s
KEMBench.decapsulate  ML-KEM-1024              thrpt    2  19250.020          ops/s
KEMBench.encapsulate   ML-KEM-512              thrpt    2  60374.724          ops/s
KEMBench.encapsulate   ML-KEM-768              thrpt    2  36226.100          ops/s
KEMBench.encapsulate  ML-KEM-1024              thrpt    2  23656.223          ops/s

Withopt:
Benchmark             (algorithm)  (provider)   Mode  Cnt      Score   Error  Units
KEMBench.decapsulate   ML-KEM-512              thrpt    2  46730.153          ops/s
KEMBench.decapsulate   ML-KEM-768              thrpt    2  28650.349          ops/s
KEMBench.decapsulate  ML-KEM-1024              thrpt    2  19390.927          ops/s
KEMBench.encapsulate   ML-KEM-512              thrpt    2  60238.211          ops/s
KEMBench.encapsulate   ML-KEM-768              thrpt    2  36454.138          ops/s
KEMBench.encapsulate  ML-KEM-1024              thrpt    2  23649.839          ops/s


System was set at fixed frequency of 2.7 Ghz during benchmarking.

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PR Review Comment: https://git.openjdk.org/jdk/pull/28815#discussion_r2679382599