Environment > Setting Preferences > !CPU Settings Preferences

# !CPU Settings Preferences

The preferences with names starting with the IDL_CPU_ prefix supply default values for the related fields of the !CPU system variable.

## IDL_CPU_TPOOL_MAX_ELTS

The IDL_CPU_TPOOL_MAX_ELTS preference sets the default value of the !CPU.TPOOL_MAX_ELTS system variable, which sets the maximum number of elements in a computation for which IDL uses the thread pool.

Committed changes take effect immediately. The default value is 0, meaning that no maximum limit is imposed, and any computation with at least !CPU.TPOOL_MIN_ELTS is a candidate for the thread pool.

This preference cannot be set in the IDL Workbench Preferences dialog.

## IDL_CPU_TPOOL_MIN_ELTS

The IDL_CPU_TPOOL_MIN_ELTS preference provides the value of the !CPU.TPOOL_MIN_ELTS system variable, which sets the number of elements in a computation that are necessary before IDL uses the thread pool to perform the work.

Committed changes take effect immediately. The default value is 100000.

This preference cannot be set in the IDL Workbench Preferences dialog.

## IDL_CPU_TPOOL_NTHREADS

The IDL_CPU_TPOOL_NTHREADS preference specifies the initial value of the !CPU.TPOOL_NTHREADS system variable, which sets the number of threads that IDL uses in thread-pool computations.

Committed changes take effect immediately. The default value is 0, which causes IDL to use a thread for every CPU contained in the system on which IDL is currently running.

This preference cannot be set in the IDL Workbench Preferences dialog.

## IDL_CPU_VECTOR_ENABLE

The IDL_CPU_VECTOR_ENABLE preference provides the initial value of the !CPU.VECTOR_ENABLE system variable if the system supports a vector unit (!CPU.HW_VECTOR is True). It is ignored if the system lacks a vector unit (!CPU.HW_VECTOR is False).

Value | Aliases
0 | False, No, Off
1 | True, Yes, On

Committed changes take effect immediately. The default value is True (1).

This preference cannot be set in the IDL Workbench Preferences dialog.