4.5. Enhancements to NUMA in Red Hat Enterprise Linux 6

This allows the operating system to detect low-level hardware details (such as logical CPUs, hyper threads, cores, sockets, NUMA nodes and access times between nodes) at boot time, and optimize processing on your system.

This new scheduling mode ensures that runtime is shared evenly between eligible processes. Combining this with topology detection allows processes to be scheduled onto CPUs within the same socket to avoid the need for expensive remote memory access, and ensure that cache content is preserved wherever possible.

malloc is now optimized to ensure that the regions of memory that are allocated to a process are as physically close as possible to the core on which the process is executing. This increases memory access speeds.

Similarly to malloc, this is now optimized to use memory that is physically close to the CPU handling I/O operations such as device interrupts.

Information recorded by device drivers about which CPU handles which interrupts can be used to restrict interrupt handling to CPUs within the same physical socket, preserving cache affinity and limiting high-volume cross-socket communication.

Typically, 90% of locks are acquired for read-only purposes. RCU locking removes the need to obtain an exclusive-access lock when the data being accessed is not being modified. This locking mode is now used in page cache memory allocation: locking is now used only for allocation or deallocation operations.

Many algorithms have been updated to perform lock coordination among cooperating CPUs on the same socket to allow for more fine-grained locking. Numerous global spinlocks have been replaced with per-socket locking methods, and updated memory allocator zones and related memory page lists allow memory allocation logic to traverse a more efficient subset of the memory mapping data structures when performing allocation or deallocation operations.