A tiny Shared Object used for optimization, brought to you by the Linux Kernel. The kernel is able to provide a memory mapping between a few Pages of its memory and the Address Space of the Program that uses the vsdo shared object. This allows the program to call Functions in the kernel’s address space as if it were part of its own address space. This is efficient, because it eliminates Context Switching from user to kernel mode and back for trivial hardware requests from the kernel that don’t really need kernel level protection, e.g. requesting the system time.