6. An apparatus comprising: a port interface unit configured to interface to a memory controller; an image processor; a translation unit coupled to the image processor and configured to cache translations for the image processor, wherein the translation unit is configured to cache each translation for a period of time that is dependent on how frequently the translation is accessed relative to other translations cached by the translation unit, wherein the translation unit is coupled to receive memory operations from the image processor and to translate virtual addresses in the memory operations, and wherein the translation unit is configured to transmit the memory operations with the translated addresses to the port interface unit; and a display pipe coupled to the port interface unit to fetch image data for display, wherein the display pipe includes one or more streaming translation units configured to prefetch translations for a plurality of virtual pages storing image data, wherein the streaming translation units are configured to discard translations of virtual pages that the display pipe has completed responsive to an indication from the display pipe that the fetch of image data from the virtual pages is completed and to prefetch one or more additional translations, wherein the display pipe is coupled to the port interface unit to transmit the fetch requests for the image data and requests to read translation data, and wherein the streaming translation units are configured to detect that fetching from the image data is being initiated, and wherein the fetch/memory management unit is configured to clear all translations and prefetch the translations for at least the first two rows of tiles in the image.
6. An apparatus comprising: a port interface unit configured to interface to a memory controller; an image processor; a translation unit coupled to the image processor and configured to cache translations for the image processor, wherein the translation unit is configured to cache each translation for a period of time that is dependent on how frequently the translation is accessed relative to other translations cached by the translation unit, wherein the translation unit is coupled to receive memory operations from the image processor and to translate virtual addresses in the memory operations, and wherein the translation unit is configured to transmit the memory operations with the translated addresses to the port interface unit; and a display pipe coupled to the port interface unit to fetch image data for display, wherein the display pipe includes one or more streaming translation units configured to prefetch translations for a plurality of virtual pages storing image data, wherein the streaming translation units are configured to discard translations of virtual pages that the display pipe has completed responsive to an indication from the display pipe that the fetch of image data from the virtual pages is completed and to prefetch one or more additional translations, wherein the display pipe is coupled to the port interface unit to transmit the fetch requests for the image data and requests to read translation data, and wherein the streaming translation units are configured to detect that fetching from the image data is being initiated, and wherein the fetch/memory management unit is configured to clear all translations and prefetch the translations for at least the first two rows of tiles in the image. 7. The apparatus as recited in claim 6 wherein the translation unit is configured, in response to a miss in the translation unit, to fetch a translation for the miss and to cache the translation.