clEnqueueNDRangeKernel
clEnqueueNDRangeKernel
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clEnqueueNDRangeKernel Enqueues a command to execute a kernel on a device.

##

cl_int `clEnqueueNDRangeKernel` cl_command_queue command_queue cl_kernel kernel cl_uint work_dim const size_t*global_work_offset const size_t*global_work_size const size_t*local_work_size cl_uint num_events_in_wait_list const cl_event*event_wait_list cl_event*event

## Parameters

`command_queue`

  A valid command-queue. The kernel will be queued for execution on the device associated with `command_queue`.

`kernel`

  A valid kernel object. The OpenCL context associated with `kernel` and `command_queue` must be the same.

`work_dim`

  The number of dimensions used to specify the global work-items and work-items in the work-group. `work_dim` must be greater than zero and less than or equal to `CL_DEVICE_MAX_WORK_ITEM_DIMENSIONS`.

`global_work_offset`

  `global_work_offset` can be used to specify an array of `work_dim` unsigned values that describe the offset used to calculate the global ID of a work-item. If `global_work_offset` is NULL, the global IDs start at offset (0, 0, ... 0).

`global_work_size`

  Points to an array of `work_dim` unsigned values that describe the number of global work-items in `work_dim` dimensions that will execute the kernel function. The total number of global work-items is computed as `global_work_size`[0] *...* `global_work_size`[`work_dim` - 1].

`local_work_size`

  Points to an array of `work_dim` unsigned values that describe the number of work-items that make up a work-group (also referred to as the size of the work-group) that will execute the kernel specified by `kernel`. The total number of work-items in a work-group is computed as `local_work_size`[0] *... * `local_work_size`[`work_dim` - 1]. The total number of work-items in the work-group must be less than or equal to the `CL_DEVICE_MAX_WORK_GROUP_SIZE` value specified in table of OpenCL Device Queries for clGetDeviceInfo and the number of work-items specified in `local_work_size`[0],... `local_work_size`[`work_dim` - 1] must be less than or equal to the corresponding values specified by `CL_DEVICE_MAX_WORK_ITEM_SIZES`[0],.... `CL_DEVICE_MAX_WORK_ITEM_SIZES`[`work_dim` - 1]. The explicitly specified `local_work_size` will be used to determine how to break the global work-items specified by `global_work_size` into appropriate work-group instances. If `local_work_size` is specified, the values specified in `global_work_size`[0],... `global_work_size`[`work_dim` - 1] must be evenly divisible by the corresponding values specified in `local_work_size`[0],... `local_work_size`[`work_dim` - 1].

  `local_work_size` can also be a NULL value in which case the OpenCL implementation will determine how to be break the global work-items into appropriate work-group instances.

`event_wait_list` and `num_events_in_wait_list`

  Specify events that need to complete before this particular command can be executed. If `event_wait_list` is NULL, then this particular command does not wait on any event to complete. If `event_wait_list` is NULL, `num_events_in_wait_list` must be 0. If `event_wait_list` is not NULL, the list of events pointed to by `event_wait_list` must be valid and `num_events_in_wait_list` must be greater than 0. The events specified in `event_wait_list` act as synchronization points. The context associated with events in `event_wait_list` and `command_queue` must be the same. The memory associated with `event_wait_list` can be reused or freed after the function returns.

`event`

  Returns an event object that identifies this particular kernel execution instance. Event objects are unique and can be used to identify a particular kernel execution instance later on. If `event` is NULL, no event will be created for this kernel execution instance and therefore it will not be possible for the application to query or queue a wait for this particular kernel execution instance.

## Notes

The work-group size to be used for `kernel` can also be specified in the program source using the `__attribute__ ((reqd_work_group_size(X, Y, Z)))` qualifier. In this case the size of work group specified by `local_work_size` must match the value specified by the `reqd_work_group_size` __attribute__ qualifier.

These work-group instances are executed in parallel across multiple compute units or concurrently on the same compute unit.

Each work-item is uniquely identified by a global identifier. The global ID, which can be read inside the kernel, is computed using the value given by `global_work_size` and `global_work_offset`. In addition, a work-item is also identified within a work-group by a unique local ID. The local ID, which can also be read by the kernel, is computed using the value given by `local_work_size`. The starting local ID is always (0, 0, ... 0).

## Errors

Returns CL_SUCCESS if the kernel execution was successfully queued. Otherwise, it returns one of the following errors:

- CL_INVALID_PROGRAM_EXECUTABLE if there is no successfully built program executable available for device associated with `command_queue`.
- CL_INVALID_COMMAND_QUEUE if `command_queue` is not a valid command-queue.
- CL_INVALID_KERNEL if `kernel` is not a valid kernel object.
- CL_INVALID_CONTEXT if context associated with `command_queue` and `kernel` is not the same or if the context associated with `command_queue` and events in `event_wait_list` are not the same.
- CL_INVALID_KERNEL_ARGS if the kernel argument values have not been specified.
- CL_INVALID_WORK_DIMENSION if `work_dim` is not a valid value (i.e. a value between 1 and 3).
- CL_INVALID_GLOBAL_WORK_SIZE if `global_work_size` is NULL, or if any of the values specified in `global_work_size`[0], ...`global_work_size` [`work_dim` - 1] are 0 or exceed the range given by the `sizeof(size_t)` for the device on which the kernel execution will be enqueued.
- CL_INVALID_GLOBAL_OFFSET if the value specified in `global_work_size` + the corresponding values in `global_work_offset` for any dimensions is greater than the `sizeof(size_t)` for the device on which the kernel execution will be enqueued.
- CL_INVALID_WORK_GROUP_SIZE if `local_work_size` is specified and number of work-items specified by `global_work_size` is not evenly divisable by size of work-group given by `local_work_size` or does not match the work-group size specified for `kernel` using the `__attribute__ ((reqd_work_group_size(X, Y, Z)))` qualifier in program source.
- CL_INVALID_WORK_GROUP_SIZE if `local_work_size` is specified and the total number of work-items in the work-group computed as `local_work_size`[0] *... `local_work_size`[`work_dim` - 1] is greater than the value specified by `CL_DEVICE_MAX_WORK_GROUP_SIZE` in the table of OpenCL Device Queries for clGetDeviceInfo.
- CL_INVALID_WORK_GROUP_SIZE if `local_work_size` is NULL and the `__attribute__ ((reqd_work_group_size(X, Y, Z)))` qualifier is used to declare the work-group size for `kernel` in the program source.
- CL_INVALID_WORK_ITEM_SIZE if the number of work-items specified in any of `local_work_size`[0], ... `local_work_size`[`work_dim` - 1] is greater than the corresponding values specified by `CL_DEVICE_MAX_WORK_ITEM_SIZES`[0], .... `CL_DEVICE_MAX_WORK_ITEM_SIZES`[`work_dim` - 1].
- CL_MISALIGNED_SUB_BUFFER_OFFSET if a sub-buffer object is specified as the value for an argument that is a buffer object and the `offset` specified when the sub-buffer object is created is not aligned to `CL_DEVICE_MEM_BASE_ADDR_ALIGN` value for device associated with `queue`.
- CL_INVALID_IMAGE_SIZE if an image object is specified as an argument value and the image dimensions (image width, height, specified or compute row and/or slice pitch) are not supported by device associated with `queue`.
- CL_INVALID_IMAGE_FORMAT if an image object is specified as an argument value and the image format (image channel order and data type) is not supported by device associated with `queue`.
- CL_OUT_OF_RESOURCES if there is a failure to queue the execution instance of `kernel` on the command-queue because of insufficient resources needed to execute the kernel. For example, the explicitly specified `local_work_size` causes a failure to execute the kernel because of insufficient resources such as registers or local memory. Another example would be the number of read-only image args used in `kernel` exceed the `CL_DEVICE_MAX_READ_IMAGE_ARGS` value for device or the number of write-only image args used in `kernel` exceed the `CL_DEVICE_MAX_WRITE_IMAGE_ARGS` value for device or the number of samplers used in `kernel` exceed `CL_DEVICE_MAX_SAMPLERS` for device.
- CL_MEM_OBJECT_ALLOCATION_FAILURE if there is a failure to allocate memory for data store associated with image or buffer objects specified as arguments to `kernel`.
- CL_INVALID_EVENT_WAIT_LIST if `event_wait_list` is NULL and `num_events_in_wait_list` > 0, or `event_wait_list` is not NULL and `num_events_in_wait_list` is 0, or if event objects in `event_wait_list` are not valid events.
- CL_OUT_OF_RESOURCES if there is a failure to allocate resources required by the OpenCL implementation on the device.
- CL_OUT_OF_HOST_MEMORY if there is a failure to allocate resources required by the OpenCL implementation on the host.

## Specification

OpenCL Specification

## Also see

clCreateCommandQueue , clGetDeviceInfo, clEnqueueNativeKernel, clEnqueueTask, Work-Item Functions

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