Physical RAM organization

The Linux kernel, at boot, organizes and partitions physical RAM into a tree-like hierarchy consisting of nodes, zones, and page frames (page frames are physical pages of RAM) (see Figure 7.19 and Figure 7.20). Nodes are divided into zones, and zones consist of page frames. A node abstracts a physical "bank" of RAM, which will be associated with one or more processor (CPU) cores. At the hardware level, the microprocessors are connected to the RAM controller chip(s); any memory controller chip, and thus any RAM, can be reached from any CPU as well, across an interconnect. Now, obviously, being able to reach the RAM physically nearest the core on which a thread is allocating (kernel) memory will lead to performance enhancement. This very idea is leveraged by hardware and OSes that support the so-called NUMA model (the meaning is explained shortly).