Abstract: Tile buffers in a graphics processing system are managed use “copy-on-write” semantics, in which tile data stored in a memory location is not transferred to another location until the tile data for one of the buffers is modified. Two memory spaces store tile data, and two logical buffers are used to access the memory spaces. For each tile, a tile association is maintained, indicating which of the two memory spaces is associated with each of the two logical buffers. To copy a tile of the first logical buffer to the second logical buffer, the tile association for the tile being copied is modified. Data for a tile is written to the memory space associated with a target logical buffer after ensuring that the tile association for the tile associates the target logical buffer with a different one of the two memory spaces from the other logical buffer.