The Kmem Allocator

The kmem allocator is modelled after an interface of similar name implemented in Solaris. This is main general purpose allocator in the kernel.

It is implemented on-top of the vmem(9) resource allocator (beyond the scope of this document), meaning it will be using pool_cache(9) internally to speed-up common (small) sized allocations.

It requires no setup, but cannot be used from interrupt context.

See kmem(9) for more details.

The Pool Allocator

The pool(9) allocator is a fixed-size memory allocator. It requires setup (to initialize a memory pool) and is interrupt-safe.

See pool(9) for more details.

The Pool Cache Allocator

The pool cache allocator works on-top of the pool(9) allocator, also allowing fixed-size allocation only, requires setup, and is interrupt-safe.

The pool cache allocator is expected to be faster than other allocators, including the “normal” pool allocator.

In the future this allocator is expected to have a per-CPU cache.

See pool_cache(9) for more details.

The UVM Kernel Memory Allocator

This is a low-level memory allocator interface. It allows variable-sized allocations in multiples of PAGE_SIZE, and can be used to allocate both wired and pageable kernel memory.

See uvm(9) for more details.