AFAIK, Antithesis uses a hypervisor to achieve deterministic execution. This can be less effective because the hypervisor does not have language semantics and faces a larger search space. You may check Figures 5 and 6 in our technical report[1], where we compare Fray against RR, a record and replay tool that can also be used for concurrency testing at OS level[2].

[1]: https://arxiv.org/pdf/2501.12618

[2]: https://robert.ocallahan.org/2016/02/introducing-rr-chaos-mo...