glBufferStorage has a flag GL_MAP_COHERENT_BIT, this flag has the following description:
Shared access to buffers that are simultaneously mapped for client access and are used by the server will be coherent, so long as that mapping is performed using glMapBufferRange. That is, data written to the store by either the client or server will be immediately visible to the other with no further action taken by the application. In particular,
If you write a value in the mapped range, how is it made visible to the other party? Is this using DMA transfers via a DMA controller? Or is there another mechanism?