If I have a multi-processor board that has cache-coherent non-uniform memory access ( NUMA ), i.e. separate “northbridges” with separate RAM for each processor, does any compiler know how to automatically spread the data across the different memory systems such that processes working on local threads are mostly retrieving their data from the RAM associated with the processor the thread is running on?
I have a setup where 1 GB is attached to processor 0, 1 GB is attached to processor 1, et c. up to 4 processors. In the coherent memory space the physical memory for the RAM on the 1st processor is addresses 0 to 1GB-1. For the second processor it is 1GB to 2GB-1, and so on.
Will any compilers, or perhaps malloc specifically, associate new memory alloc’d by a process on a specific core to the physical RAM associated with that core?
Linux kernel knows about NUMA and will try to give your process pages from memory local to the current CPU (source: U. Drepper, “What Every Programmer Should Know About Memory”.)