• Of course, there is much more to OpenMP than that, but the concept of having automatic parallelization is a main advantage of OpenMP.
  • OpenMP is an open source library which is used for multi-threaded parallel processing and shared-memory multi-processor (core) computers.
  • – Directives are instructions to a compiler – API also has library routines and environment variables. • Specification by OpenMP Architecture Review Board (ARB).
  • Using OpenMP with C¶. Because a cluster consists of many CPUs, the most effective way to utilize these resources involves parallel programming.
  • The OpenMP [1] specification describes a collection of compiler directives for marking regions of code for parallel execution and synchronization.
  • In general an OpenMP program starts with a sequential section in which it sets up the environment, initializes the variables, and so on.
  • – Mul)ple CPUs share global memory, could have local cache – Uniform Memory Access (UMA) – Typical Shared Memory Programming Model: OpenMP
  • OpenMP (Open Multi-­Processing). – Application Program Interface (API) – Governed by OpenMP Architecture Review Board.
  • Enabling OpenMP is (surprisingly) as simple as its basic usage. Let’s look at how we can enabled OpenMP using either g++ only or as part of a CMake project.
  • Size of these stacks is not defined by OpenMP standards Intel compiler: default stack is 4MB gcc/gfortran: default stack is 2MB.