Z Load Store

For most renders, depth and stencil buffers only contain temporary data required to complete the associated render pass. In the PowerVR architecture, on-chip depth and stencil buffers are used to store this data. When the appropriate API mechanisms are utilised (please refer to our Performance Recommendations document for more information), an application will never cause data to be uploaded to or written from these on-chip buffers. This enables an application to avoid redundant system memory transfers for these temporary buffers.

A Z load store event indicates that there has been an upload or resolve of depth/stencil data to/from the GPU. Unless a given application requires depth or stencil information to be preserved, an application should always use the appropriate API mechanisms to avoid these costly data transfer operations.

A value above 0% indicates a Z load store event has occurred. To avoid these operations, you should ensure depth and stencil buffers that do not need to be preserved are cleared at the start and invalidated at the end of each render pass.