Visible to Intel only — GUID: GUID-BD9B39A7-5885-4C6C-A047-93F22EB85740
Visible to Intel only — GUID: GUID-BD9B39A7-5885-4C6C-A047-93F22EB85740
Intel® Compiler Extension Routines to OpenMP*
The Intel® compiler implements the following group of routines as extensions to the OpenMP* runtime library:
Get and set the execution environment
Get and set the stack size for parallel threads
Memory allocation
Get and set the thread sleep time for the throughput execution mode
Target memory allocation
The Intel® extension routines described in this section can be used for low-level tuning to verify that the library code and application are functioning as intended. These routines are generally not recognized by other OpenMP-compliant compilers, which may cause the link stage to fail in the other compiler. To execute these OpenMP routines, use the /Qopenmp-stubs (Windows*) or -qopenmp-stubs (Linux*) option.
In most cases, environment variables can be used in place of the extension library routines. For example, the stack size of the parallel threads may be set using the OMP_STACKSIZE environment variable rather than the KMP_SET_STACKSIZE_S() library routine.
A runtime call to an Intel extension routine takes precedence over the corresponding environment variable setting.
Execution Environment
Function or Subroutine |
Description |
---|---|
SUBROUTINE KMP_SET_DEFAULTS(STRING) CHARACTER*(*) STRING |
Sets OpenMP environment variables defined as a list of variables separated by "|" in the argument. |
SUBROUTINE KMP_SET_LIBRARY_THROUGHPUT() |
Sets execution mode to throughput, which is the default. Allows the application to determine the runtime environment. Use in multi-user environments. |
SUBROUTINE KMP_SET_LIBRARY_TURNAROUND() |
Sets execution mode to turnaround. Use in dedicated parallel (single user) environments. |
SUBROUTINE KMP_SET_LIBRARY_SERIAL() |
Sets execution mode to serial. |
SUBROUTINE KMP_SET_LIBRARY(LIBNUM) INTEGER (KIND=OMP_INTEGER_KIND) LIBNUM |
Sets execution mode indicated by the value passed to the function. Valid values are:
Call this routine before the first parallel region is executed. |
FUNCTION KMP_GET_LIBRARY() INTEGER (KIND=OMP_INTEGER_KIND) KMP_GET_LIBRARY |
Returns a value corresponding to the current execution mode:
|
Stack Size
Function or Subroutine |
Description |
---|---|
FUNCTION KMP_GET_STACKSIZE_S() INTEGER (KIND=KMP_SIZE_T_KIND) & KMP_GET_STACKSIZE_S |
Returns the number of bytes that will be allocated for each parallel thread to use as its private stack. This value can be changed with KMP_SET_STACKSIZE_S() routine, prior to the first parallel region or via the KMP_STACKSIZE environment variable. |
FUNCTION KMP_GET_STACKSIZE() INTEGER KMP_GET_STACKSIZE |
Provided for backwards compatibility only. Use KMP_GET_STACKSIZE_S() routine for compatibility across different families of Intel processors. |
SUBROUTINE KMP_SET_STACKSIZE_S(size) INTEGER (KIND=KMP_SIZE_T_KIND) size |
Sets to size the number of bytes that will be allocated for each parallel thread to use as its private stack. This value can also be set via the KMP_STACKSIZE environment variable. In order for KMP_SET_STACKSIZE_S() to have an effect, it must be called before the beginning of the first (dynamically executed) parallel region in the program. |
SUBROUTINE KMP_SET_STACKSIZE_S(size) INTEGER size |
Provided for backward compatibility only. Use KMP_SET_STACKSIZE_S(size) for compatibility across different families of Intel® processors. |
Memory Allocation
The Intel® compiler implements a group of memory allocation routines as an extension to the OpenMP runtime library to enable threads to allocate memory from a heap local to each thread. These routines are: KMP_MALLOC(), KMP_CALLOC(), and KMP_REALLOC().
The memory allocated by these routines must also be freed by the KMP_FREE() routine. While you can allocate memory in one thread and then free that memory in a different thread, this mode of operation incurs a slight performance penalty.
Working with the local heap might lead to improved application performance because synchronization is not required.
Function or Subroutine |
Description |
---|---|
FUNCTION KMP_MALLOC(size) INTEGER(KIND=KMP_POINTER_KIND)KMP_MALLOC INTEGER(KIND=KMP_SIZE_T_KIND size |
Allocates memory block of size bytes from thread-local heap. |
FUNCTION KMP_CALLOC(nelem, elsize) INTEGER(KIND=KMP_POINTER_KIND)KMP_CALLOC INTEGER(KIND=KMP_SIZE_T_KIND) nelem INTEGER(KIND=KMP_SIZE_T_KIND) elsize |
Allocates array of nelem elements of size elsize from thread-local heap. |
FUNCTION KMP_REALLOC(ptr, size) INTEGER(KIND=KMP_POINTER_KIND)KMP_REALLOC INTEGER(KIND=KMP_POINTER_KIND) ptr INTEGER(KIND=KMP_SIZE_T_KIND) size |
Reallocates memory block at address ptr and size bytes from thread-local heap. |
SUBROUTINE KMP_FREE(ptr) INTEGER (KIND=KMP_POINTER_KIND) ptr |
Frees memory block at address ptr from thread-local heap. The memory must have been previously allocated with KMP_MALLOC(), KMP_CALLOC(), or KMP_REALLOC(). |
Thread Sleep Time
In the throughput OpenMP* Support Libraries, threads wait for new parallel work at the ends of parallel regions, and then sleep, after a specified period of time. This time interval can be set by the KMP_BLOCKTIME environment variable or by the KMP_SET_BLOCKTIME() function.
Function |
Description |
---|---|
FUNCTION KMP_GET_BLOCKTIME() INTEGER KMP_GET_BLOCKTIME |
Returns the number of milliseconds that a thread should wait, after completing the execution of a parallel region, before sleeping, as set either by the KMP_BLOCKTIME environment variable or by KMP_SET_BLOCKTIME(). |
FUNCTION KMP_SET_BLOCKTIME(msec) INTEGER msec |
Sets the number of milliseconds that a thread should wait, after completing the execution of a parallel region, before sleeping. This routine affects the block time setting for the calling thread and any OpenMP team threads formed by the calling thread. The routine does not affect the block time for any other threads. |
Target Memory Allocation
Function | Description |
---|---|
FUNCTION ompx_target_aligned_alloc (align, size, & device_num) USE,INTRINSIC :: ISO_C_BINDING, ONLY : C_PTR, & C_SIZE_T, C_INT TYPE(C_PTR) :: ompx_target_aligned_alloc INTEGER(C_SIZE_T) :: align INTEGER(C_SIZE_T) :: size INTGER(C_INT) :: device_num |
Allocates device memory that is aligned to the specified alignment argument align for the specified device device_num. The returned memory can be accessed only by the specified device. |
FUNCTION ompx_target_aligned_alloc_device (align, & size, device_num) USE,INTRINSIC :: ISO_C_BINDING, ONLY : C_PTR, & C_SIZE_T, C_INT TYPE(C_PTR) :: ompx_target_aligned_alloc_device INTEGER(C_SIZE_T) :: align INTEGER(C_SIZE_T) :: size INTGER(C_INT) :: device_num |
Allocates device memory that is aligned to the specified alignment argument align for the specified device device_num. The returned memory can be accessed only by the specified device. |
FUNCTION ompx_target_aligned_alloc_host (align, & size, device_num) USE,INTRINSIC :: ISO_C_BINDING, ONLY : C_PTR, & C_SIZE_T, C_INT TYPE(C_PTR) :: ompx_target_aligned_alloc_host INTEGER(C_SIZE_T) :: align INTEGER(C_SIZE_T) :: size INTGER(C_INT) :: device_num |
Allocates device memory that is aligned to the specified alignment argument align for the specified device device_num. The returned memory can be accessed by the host and all supported devices. |
FUNCTION ompx_target_aligned_alloc_shared (align, & size, device_num) USE,INTRINSIC :: ISO_C_BINDING, ONLY : C_PTR, & C_SIZE_T, C_INT TYPE(C_PTR) :: ompx_target_aligned_alloc_shared INTEGER(C_SIZE_T) :: align INTEGER(C_SIZE_T) :: size INTGER(C_INT) :: device_num |
Allocates device memory that is aligned to the specified alignment argument align for the specified device device_num. The returned memory can be accessed by the host and the specified device. |
FUNCTION & ompx_target_aligned_alloc_shared_with_hint (align, & size, access_hint, device_num) USE,INTRINSIC :: ISO_C_BINDING, ONLY : C_PTR, & C_SIZE_T, C_INT USE OMP_LIB_KINDS TYPE(C_PTR) :: ompx_target_aligned_alloc_shared INTEGER(C_SIZE_T) :: align INTEGER(C_SIZE_T) :: size INTGER(OMP_INTEGER_KIND) :: access_hint INTGER(OMP_INTEGER_KIND) :: device_num |
Allocates device memory that is aligned to the specified alignment argument align for the specified device device_num with the specified access_hint. The returned memory can be accessed by the host and the specified device. The following named constants are allowed for access_hint:
|
FUNCTION omp_target_alloc_host (size, device_num) USE, INTRINSIC :: ISO_C_BINDING TYPE(C_PTR) :: omp_target_alloc_host INTEGER(c_size_t) :: size INTEGER(c_int) :: device_num |
Returns the address of a storage location that is size bytes in length allocated in host memory. The same pointer can be used to access the memory on the host and all supported devices. If the allocation request fails, a null pointer is returned. |
FUNCTION omp_target_alloc_device (size, device_num) USE, INTRINSIC :: ISO_C_BINDING TYPE(C_PTR) :: omp_target_alloc_device INTEGER(c_size_t) :: size INTEGER(c_int) :: device_num |
Returns the address of a storage allocation that is size bytes in length. Device allocations are owned by the device specified by device_num in device memory if present. Generally, the allocation can be accessed only by the device, but it can be copied to other device or host allocated memory. If the allocation was not successful, a null pointer is returned. |
FUNCTION omp_target_alloc_shared (size, device_num) USE, INTRINSIC :: ISO_C_BINDING TYPE(C_PTR) :: omp_target_alloc_shared INTEGER(c_size_t) :: size INTEGER(c_int) :: device_num |
Returns the address of a storage allocation that is size bytes in length. The same pointer may be used to access the memory on the host and the specified device. Shared allocations are shared by the host and the specified device, and are intended to migrate between the host and the device. If the allocation was not successful, a null pointer is returned. |
FUNCTION omp_target_realloc (ptr, size, device_num) USE, INTRINSIC :: ISO_C_BINDING, ONLY C_PTR, & TYPE (C_PTR) :: ompx_target_realloc TYPE (C_PTR),VALUE :: ptr INTEGER(C_SIZE_T) :: size INTEGER(C_INT) :: device_num |
Deallocates the device memory specified with ptr and allocates a new device memory with the specified size in bytes for the given device device_num. The returned memory can be accessed only by the specified device. The contents of the new memory object are the same as that of the old object prior to deallocation up to the minimum size of old allocated size and size argument. |
FUNCTION ompx_target_realloc_device (ptr, size, & device_num) USE,INTRINSIC :: ISO_C_BINDING, ONLY: C_PTR, & C_SIZE_T, C_INT TYPE(C_PTR) :: ompx_target_realloc_device TYPE(C_PTR) :: ptr INTEGER(C_SIZE_T) :: size INTEGER(C_INT) :: device_num |
Deallocates the device memory specified with ptr and allocates a new device memory with the specified size in bytes for the given device device_num. The returned memory can be accessed only by the specified device. The contents of the new memory object are the same as that of the old object prior to deallocation up to the minimum size of old allocated size and size argument. |
FUNCTION ompx_target_realloc_host (ptr, size, & device_num) USE,INTRINSIC :: ISO_C_BINDING, ONLY: C_PTR, & C_SIZE_T, C_INT TYPE(C_PTR) :: ompx_target_realloc_host TYPE(C_PTR) :: ptr INTEGER(C_SIZE_T) :: size INTEGER(C_INT) :: device_num |
Deallocates the device memory specified with ptr and allocates a new device memory with the specified size in bytes for the given device device_num. The returned memory can be accessed by the host and all supported devices. The contents of the new memory object are the same as that of the old object prior to deallocation up to the minimum size of old allocated size and size argument. |
FUNCTION ompx_target_realloc_shared (ptr, size, & device_num) USE,INTRINSIC :: ISO_C_BINDING, ONLY: C_PTR, & C_SIZE_T, C_INT TYPE(C_PTR) :: ompx_target_realloc_shared TYPE(C_PTR) :: ptr INTEGER(C_SIZE_T) :: size INTEGER(C_INT) :: device_num |
Deallocates the device memory specified with ptr and allocates a new device memory with the specified sizein bytes for the given device device_num. The returned memory can be accessed by the host and the specified device. The contents of the new memory object are the same as that of the old object prior to deallocation up to the minimum size of old allocated size and size argument. |
Target Offload
Function or Subroutine | Description |
---|---|
FUNCTION omp_get_device_from_ptr (ptr) USE OMP_LIB_KINDS USE,INTRINSIC :: ISO_C_BINDING, ONLY : C_PTR INTEGER(OMP_INTEGER_KIND) :: omp_get_device_from_ptr TYPE(C_PTR) :: ptr |
Returns OpenMP device number which the specified device pointer ptr is allocated on. The function returns a valid OpenMP device number if successful; otherwise, a negative number. |
FUNCTION ompx_get_num_subdevices (device_num, level) USE,INTRINSIC :: ISO_C_BINDING, ONLY : C_INT INTEGER(C_INT) ompx_get_num_subdevices INTEGER(C_INT) :: device_num INTEGER(C_INT :: level |
Returns the number of subdevices supported by the given device ID (device_num) at the specified level. |
FUNCTION ompx_target_register_host_pointer (ptr, size, & device_num) USE omp_lib_kinds USE, INTRINSIC :: ISO_C_BINDING, ONLY : C_PTR, C_SIZE_T INTEGER(omp_integer_kind) ompx_target_rester_host_pointer TYPE(C_PTR) :: ptr INTEGER(C_SIZE_T) :: size INTEGER(omp_integer_kind) :: device_num |
Registers the specified host pointer ptr for efficient memory copy between ptr and a device pointer allocated for device_num. The function returns a non-zero value if successful; otherwise, zero.
NOTE:
This is only available for Linux. |
SUBROUTINE ompx_target_unregister_host_pointer (ptr, & device) USE omp_lib_kinds USE,INTRINSIC :: ISOC_C_BINDING : ONLY C_PTR TYPE(C_PTR) :: ptr INTEGER(omp_integer_kind) :: device |
Unregisters the specified host pointer ptr.
NOTE:
This is only available for Linux. |