Solaris™ Internals: Core Kernel Components

6.2. Kernel Memory Allocation

Kernel memory is allocated at different levels, depending on the desired allocation characteristics. At the lowest level is the page allocator, which allocates unmapped pages from the free lists so the pages can then be mapped into the kernel's address space for use by the kernel.

Allocating memory in pages works well for memory allocations that require page-sized chunks, but there are many places where we need memory allocations smaller than one page; for example, an in-kernel inode requires only a few hundred bytes per inode, and allocating one whole page (8 Kbytes) would be wasteful. For this reason, Solaris has an object-level kernel memory allocator in addition to the page-level allocator to allocate arbitrarily ...