RFR: 8366441: AArch64: Support WFET in OnSpinWait [v3]

[Andrew Haley]

On Tue, 10 Feb 2026 07:21:57 GMT, Per Minborg <pminborg at openjdk.org> wrote:

> Unless the default value is changed, this will have a relatively large impact on certain low-latency applications where one waits for a CAS-lock in a spin loop. Latencies in such applications are often measured in ns. So, this is something that should be communicated to the community in some way.

Thanks. Do you have an idea of what you'd like to see?

I think cache coherence protocols have about 40ns latency between cores in a socket, so would that be a sensible default?

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PR Comment: https://git.openjdk.org/jdk/pull/27030#issuecomment-3877500000