Environment Variables (GNU libgomp) (original) (raw)

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4 OpenMP Environment Variables ¶

The environment variables which beginning with OMP_ are defined by section 4 of the OpenMP specification in version 4.5 or in a later version of the specification, while those beginning with GOMP_ are GNU extensions. Most OMP_ environment variables have an associated internal control variable (ICV).

For any OpenMP environment variable that sets an ICV and is neitherOMP_DEFAULT_DEVICE nor has global ICV scope, associated device-specific environment variables exist. For them, the environment variable without suffix affects the host. The suffix _DEV_ followed by a non-negative device number less that the number of available devices sets the ICV for the corresponding device. The suffix _DEV sets the ICV of all non-host devices for which a device-specific corresponding environment variable has not been set while the _ALL suffix sets the ICV of all host and non-host devices for which a more specific corresponding environment variable is not set.

• OMP_ALLOCATOR – Set the default allocator
• OMP_AFFINITY_FORMAT – Set the format string used for affinity display
• OMP_CANCELLATION – Set whether cancellation is activated
• OMP_DISPLAY_AFFINITY – Display thread affinity information
• OMP_DISPLAY_ENV – Show OpenMP version and environment variables
• OMP_DEFAULT_DEVICE – Set the device used in target regions
• OMP_DYNAMIC – Dynamic adjustment of threads
• OMP_MAX_ACTIVE_LEVELS – Set the maximum number of nested parallel regions
• OMP_MAX_TASK_PRIORITY – Set the maximum priority
• OMP_NESTED – Nested parallel regions
• OMP_NUM_TEAMS – Specifies the number of teams to use by teams region
• OMP_NUM_THREADS – Specifies the number of threads to use
• OMP_PROC_BIND – Whether threads may be moved between CPUs
• OMP_PLACES – Specifies on which CPUs the threads should be placed
• OMP_STACKSIZE – Set default thread stack size
• OMP_SCHEDULE – How threads are scheduled
• OMP_TARGET_OFFLOAD – Controls offloading behavior
• OMP_TEAMS_THREAD_LIMIT – Set the maximum number of threads imposed by teams
• OMP_THREAD_LIMIT – Set the maximum number of threads
• OMP_WAIT_POLICY – How waiting threads are handled
• GOMP_CPU_AFFINITY – Bind threads to specific CPUs
• GOMP_DEBUG – Enable debugging output
• GOMP_STACKSIZE – Set default thread stack size
• GOMP_SPINCOUNT – Set the busy-wait spin count
• GOMP_RTEMS_THREAD_POOLS – Set the RTEMS specific thread pools