This becomes particularly important when the allocation and metadata cannot (or should not) be stored in the same address space. An example of this is allocating memory on GPUs.

The conventional approach for allocating memory on GPUs for games and other applications is to use a real-time allocator such as TLSF. However, it is not usually discussed that TLSF is real-time because it stores metadata in-band. It is possible to create a variant of TLSF that preserves its real-time properties while storing metadata out-of-band, but this requires careful consideration.