The Cray Shared Memory Access (SHMEM) library routines are similar to one-directional MPI-2 routines; they pass data between co-operating parallel processes with active action from only one of the processes. The name of the library stems from its past usage on physically shared memory architectures.

Like MPI, the Cray SHMEM library is implemented on top of the Portals low-level message-passing engine.

More information on using SHMEM can be found in Cray Application Developer's Environment User's Guide and Workload Management and Application Placement for the Cray Linux Environment, see http://docs.cray.com, or, or by the command man shmem or man intro_shmem.