[crac] RFR: RFC: -XX:CPUFeatures=0xnumber for CPU migration [v8]

[Anton Kozlov]

On Wed, 1 Mar 2023 11:46:18 GMT, Jan Kratochvil <duke at openjdk.org> wrote:

> I could split the patch but it is not testable/usable without the CPU count fix/hack.

Maybe getting CPU count change first is a way to go? I understand that migration between different CPU features depends on CPU count change, but the CPU count is isolated and can be done upfront, right? Since we are waiting for glibc anyway for CPU features. But still we can meet with a different number of CPUs with the same feature set.

Does the CPU count problem appear if a container is started with different quotas, like docker's `--cpu`? [1]
Or does it require a different number of physical CPU cores?

https://docs.docker.com/config/containers/resource_constraints/#cpu

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PR: https://git.openjdk.org/crac/pull/41