DYNAMIC DATA CACHE INVALIDATE WITH DATA DEPENDENT EXPIRATION

摘要

A method for invalidating a dynamic data cache with data dependent expiration and an image processing system are provided to use a distribution type time based signal and attribute bits within a memory directory entry, thereby effectively invalidating a part of the memory cache where address conversion is provided by the memory directory entry. An image processing system generates a static space index showing a static object within a three-dimensional scene and generates a dynamic pace index showing all dynamic objects within the three-dimensional scene(705). The image processing system respectively stores the static and dynamic space indexes in static and dynamic space index parts of a memory cache(710,715). The image processing system performs ray tracing for a rendered current frame(720). The image processing system invalidates the dynamic part of the memory cache(725). The image processing system determines whether it is the time to update the static space index(730). If not so, the image processing system generates a new dynamic space index which can be used to render the next frame(735). A method for invalidating data within the memory cache comprises the following steps of: generating a first memory directory entry corresponding to a first part of the memory cache and a second memory directory entry corresponding to a second part of the memory cache; setting a first bit within the first memory directory entry so as to display that the first memory directory entry is invalid when receiving a distribution type time based signal; generating the distribution type time based signal; setting a second bit of the first and second memory directory entries in response to the distribution type time based signal; receiving a memory address conversion request for the first part of the memory cache; and determining whether the first memory directory entry is invalid by inspecting the first and second bits within the first memory directory entry.