SPUM: A Screen Partition Update Method for Embedded Multi-Window Systems

This paper proposes a screen partition update method (SPUM) for embedded multi-window systems with the purpose of improving their display performance. In this method the whole screen is partitioned into multiple independent sub-regions according to the position and size information of application windows at first and the overlap degree of each sub-region is calculated afterwards. Each window has an associated bitmap used to mark which sub-regions on the whole screen are contained by this window and which are not. When one application window updates, sub-regions of this window are updated step by step. In order to reduce the probability of conflict, the free sub-region with bigger overlap degree is updated preferentially. This method increases the probability of parallel update. When we apply the SPUM algorithm into an actual DirectFB graphics system, the total window update time cost is reduced by 35% and the conflict number is decreased by 72% in our experiment. Further experiment shows that with the increase of refresh rate the performance improvement introduced by the algorithm is more notable.