Comment by nimrody

"While early microkernel work saw significant performanceoverheads attributed to inter-process communication (IPC)and address space changes [15,16,20], such overheads areless significant today. Compared to the uniprocessor systemsof the 80s and 90s, today’s servers contain dozens of cores,which allows microkernel invocation to leverage inter-coreIPC while maintaining application cache locality. This ap-proach can evenimproveoverall performance when there islittle state to communicate across the IPC (common in zero-copy networking) and in avoiding ring switch costs of systemcalls. Moreover, recent security vulnerabilities such as Melt-down [43] force kernel/user address space isolation, even inmonolithic kernels [25]. Techniques like tagged-TLB supportin modern processors, streamlined ring switching hardwaremade necessary with the resurgence of virtualization, andIPC optimization techniques such as those explored in theL4 microkernel [29], in FlexSC [58], and in SkyBridge [44],further allow a modern microkernel to essentially close theperformance gap between direct system calls and indirectsystem calls through IPC."