RFR: 8370947: Mitigate Neoverse-N1 erratum 1542419 negative impact on GCs and JIT performance [v25]

[Evgeny Astigeevich]

On Mon, 9 Feb 2026 13:01:32 GMT, Andrew Haley <aph at openjdk.org> wrote:

> > > @theRealAph @shipilev @fisk Any other tests to run in addition to the suggested tests above?
> > 
> > 
> > It all goes back to the question I asked before. If we run this test on all Neoverse N1, not just the affected stepping, would there be any disadvantage?
> 
> Sorry, i mean if we run the same workaround code on all Neoverse N1. Why not? Would it be slower?

I don't have unaffected N1 to check. Out of curiosity, does unaffected N1 exist in any cloud?

I think it would not be slower.

Unaffected N1 will be running the following code, as V1 and V2, once per patched nmethod:

dsb ish
isb


[Graviton 3(Neoverse V1) results](https://github.com/openjdk/jdk/pull/28328#issuecomment-3585923078) show benefits of the deferred invalidation as well. So should unaffected N1. An explanation of the improvement is in the comment: https://github.com/openjdk/jdk/pull/28328#issuecomment-3585923078.

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PR Comment: https://git.openjdk.org/jdk/pull/28328#issuecomment-3871928510