« on: February 17, 2015, 09:11:40 PM »
It appeared in ARB_buffer_storage and it become core in OpenGL 4.4. It allows you to map buffer once and keep the pointer forever. No need to unmap it and release the pointer to the driver... all the magic happens underneath.
Persistent Mapping is also included in modern OpenGL set of techniques called AZDO - Aproaching Zero Driver Overhead. As you can imagine, by mapping buffer only once we significantly reduce number of heavy OpenGL function calls and what's more important, fight synchronization problems.