The aprun CPU Affinity Option

Using the aprunCPU affinity option may improve application performance.

CNL can dynamically distribute work by allowing PEs and threads to migrate from one CPU to another within a node. In some cases, moving processes from CPU to CPU increases cache misses and translation lookaside buffer (TLB) misses and therefore reduces performance. Also, there may be cases where an application runs faster by avoiding or targeting a particular CPU. The aprun CPU affinity options enables a user to bind a process to a particular CPU or the CPUs on a NUMA node. These options apply to all Cray multicore compute nodes.

Applications are assigned to a cpuset and can run only on the CPUs specified by the cpuset. Also, applications can allocate memory only on memory defined by the cpuset. A cpuset can be a compute node (default) or a NUMA node.

For details, see Run Applications Using the aprun Command.