OpenMP Introduction

- Threads

• Master Thread has id 0

- Sections

• The SECTIONS directive is a non-iterative work-sharing construct. It specifies that the enclosed section(s) of code are to be divided among the threads in the team

• Independent SECTION directives are nested within a SECTIONS directive. Each SECTION is executed once by a thread in the team. Different sections may be executed by different threads.

• It is possible for a thread to execute more than one section if it is quick enough and the implementation permits

- Single

• The SINGLE directive specifies that the enclosed code is to be executed by only one thread in the team.

• May be useful when dealing with sections of code that are not thread safe
• It is illegal to branch into or out of a SINGLE block

Environment Variables

• OMP_NUM_THREADS