How does PIs Direct Rendering improve performance over Indirect Rendering?
PI’s Direct Rendering scheme improves performance in several ways: 1) The DRI uses the X Server to manage and coordinate data transfer directly between an application and the graphics hardware, but it does not copy the drawing commands and data between the application and the X Server. Indirect rendering schemes involve an intermediate transfer of application drawing commands or data from the application space. This requires encoding the data according to the X11 core or extension protocol, transmission to the X Server data space by some interprocess communication, and final decoding and interpretation by the X Server. The extra CPU overhead is avoided when using direct renderings. 2) Indirect rendering introduces intermediate buffering of data which places delays between the time the application issues a drawing command and the time the command actually gets exectued. These delays can cause the graphics hardware to be idle even though there are commands to execute in the buffer, and i
