Paper: LLFree: Scalable and Optionally-Persistent Page-Frame Allocation https://www.usenix.org/system/files/atc23-wrenger.pdf
Video presentation: https://www.youtube.com/watch?v=yvd3D5VOHc8
Implementation and benchmarks are well documented at the repos:
Rust repo https://github.com/luhsra/llfree-rs C repo https://github.com/luhsra/llfree-c