Add NUMA-awareness to allocators

[lukemartinlogan]

We need to have the ability to choose the NUMA node where memory is allocated from.

Three options:

1. Make this apart of the MemoryBackend.

• MemoryBackend would contain a vector of (char*,string) tuples.
• Would have to add an API to the backend for querying NUMA
• Would have to add an API to the allocator for querying NUMA
• Would need to update backend to support multiple mappings

2. Make this apart of an Allocator.

• Would need to add an API to the allocator for querying NUMA
• Would need to add a vector to allocator support multiple mapping

3. Make this apart of the specific data structure

• User will need to know which allocators belong to which NUMA node
• Could add an API to memory manager to create an allocator per NUMA node
• Could add an Allocator takes those allocators as input, and internally determines the NUMA node of the process.

Option 3 is the best. It requires no changes to MemoryBackend or Allocator. Only a NUMA-aware backend and a simple wrapper allocator need to be added.

• Add backend which enables mapping of a specific NUMA node
• Add allocator which takes as input a vector of pairs of allocators
• Add AllocateNuma* wrapper functions