Cache coloring

Cache Coloring or Page Coloring is the process by which memory allocation code will attempt to locate free pages that are contiguous from the point of view of the cache. For example, if page 10 of physical memory is assigned to page 0 of a process's virtual memory and the cache can hold 5 pages, the page coloring code will not assign page 15 of physical memory to page 1 of a process's virtual memory. It would, instead, assign page 21 of physical memory. The page coloring code attempts to avoid assigning page 15 because this maps over the same cache memory as page 10 and would result in non-optimal caching. This code adds a significant amount of complexity to the VM memory allocation subsystem, but the result is well worth the effort. Page Coloring makes VM memory as deterministic as physical memory in regards to cache performance.