Restartable Sequences “RSEQ” has been one of the nice additions to the Linux kernel in recent years and can allow for faster user-space operations on per-CPU data by providing a shared data structure ABI between each user-space thread and the kernel. RSEQ has been in the process of being extended to provide even more performance benefits…

Source: Phoronix – Linux RSEQ Patches Updated For Allowing Faster getcpu() In C Libraries