Mastering Linux Kernel Development

Slab allocator

As discussed in earlier sections, the page allocator (in coordination with buddy system) does an efficient job of handling memory allocation requests in multiples of page size. However, most allocation requests initiated by kernel code for its internal use are for smaller blocks (usually less than a page); engaging the page allocator for such allocations results in internal fragmentation, causing wastage of memory. The slab allocator is implemented precisely to address this; it is built on top of the buddy system and is used to allocate small memory blocks, to hold structure objects or data used by kernel services.

Design of the slab allocator is based on an idea of object cache. The concept of an object cache is quite simple: ...