RFR: 8377597: [Leyden] Improve peak performance when AOT code is used [v2]

[Aleksey Shipilev]

On Thu, 12 Feb 2026 17:42:32 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

> But A4 is replaced with T4 which does not have this counter. So it slightly affects only AOT code which is used only during startup.

We differ on the "slightly", I think. We have seen 10x performance hits on unlucky T3 contentions. Are we sure we can afford that kind of slowdown for A4 code, especially when A4 -> T4 replacement can take tens of seconds? I am not so sure at all.

But really I think it is not a fundamental design problem, it is an engineering problem: I believe this counter should be at very least probabilistic to manage contention, like in [JDK-8372701](https://bugs.openjdk.org/browse/JDK-8372701).

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PR Comment: https://git.openjdk.org/leyden/pull/110#issuecomment-3892430178