Introducing kernel memory allocators

The Linux kernel, like any other OS, requires a sturdy algorithm and implementation to perform a really key task – the allocation and subsequent deallocation of memory or page frames (RAM). The primary (de)allocator engine in the Linux OS is referred to as the PA, or the BSA. Internally, it uses a so-called buddy system algorithm to efficiently organize and parcel out free chunks of system RAM. We will find more on the algorithm in the Understanding and using the kernel page allocator (or BSA) section.

In this chapter and in this book, when we use the notation (de)allocate, please read it as both words: allocate and deallocate.

Of course, being imperfect, the page allocator is not the only or always the best way to obtain and subsequently release system memory. Other technologies exist within the Linux kernel to do so. High on the list of them is the kernel's slab allocator or slab cache system (we use the word...