Transaction Elimination (TE) is a key bandwidth saving feature of the Arm Mali Midgard and BiFrost GPU architecture which allows for significant energy savings on a System on Chip (SoC) level. When performing TE, the GPU compares the current frame buffer with the previously rendered frame and performs a partial update only to the particular parts of it that have been modified, thus significantly reducing the amount of data that need to be transmitted per frame to external memory. The comparison is done on a per tile basis, using a Cyclic Redundancy Check (CRC) signature to determine if the tile has been modified. Tiles with the same CRC signature are identical; therefore eliminating them has no impact to the resulting image quality. TE can be used by every application for all frame buffer formats supported by the GPU, irrespective of the frame buffer precision requirements. Transaction Elimination is highly effective, even on first-person shooter (FPS) games and video. However, considering the fact that in many other popular graphics applications, such as User Interfaces and casual games, large parts of the frame buffer remain static between two consecutive frames, frame buffer bandwidth savings from Transaction Elimination can reach up to 99%.
Some of the key features of Transaction Elimination are:
- No impact to image quality
- Agnostic of frame buffer format
- Per tile comparison between frame buffers
- 16x16 pixels tile size
- CRC-based signature comparison