2.10. numad

numad is an automatic NUMA affinity management daemon. It monitors NUMA topology and resource usage within a system in order to dynamically improve NUMA resource allocation and management (and therefore system performance). Depending on system workload, numad can provide up to 50 percent improvements in performance benchmarks. It also provides a pre-placement advice service that can be queried by various job management systems to provide assistance with the initial binding of CPU and memory resources for their processes.

numad monitors available system resources on a per-node basis by periodically accessing information in the /proc file system. It tries to maintain a specified resource usage level, and rebalances resource allocation when necessary by moving processes between NUMA nodes. numad attempts to achieve optimal NUMA performance by localizing and isolating significant processes on a subset of the system's NUMA nodes.

numad primarily benefits systems with long-running processes that consume significant amounts of resources, and are contained in a subset of the total system resources. It may also benefit applications that consume multiple NUMA nodes' worth of resources; however, the benefits provided by numad decrease as the consumed percentage of system resources increases.

numad is unlikely to improve performance when processes run for only a few minutes, or do not consume many resources. Systems with continuous, unpredictable memory access patterns, such as large in-memory databases, are also unlikely to benefit from using numad.

For further information about using numad, see Section 6.3.5, “Automatic NUMA Affinity Management with numad” or Section A.13, “numad”, or refer to the man page:

$ man numad