clGetCommandQueueInfo

Query information about a command-queue.

`cl_int clGetCommandQueueInfo (`	cl_command_queue `command_queue` ,
	cl_command_queue_info `param_name` ,
	size_t `param_value_size` ,
	void `*param_value` ,
	size_t `*param_value_size_ret` `)`

Parameters

command_queue

Specifies the command-queue being queried.

param_name

Specifies the information to query.

param_value_size

Specifies the size in bytes of memory pointed to by param_value. This size must be ≥ size of return type as described in the table below. If param_value is NULL, it is ignored.

param_value

A pointer to memory where the appropriate result being queried is returned. If param_value is NULL, it is ignored.

param_value_size_ret

Returns the actual size in bytes of data being queried by param_value. If param_value_size_ret is NULL, it is ignored.

The list of supported param_name values and the information returned in param_value by clGetCommandQueueInfo is described in the table below.

cl_command_queue_info	Return Type and Information returned in param_value
`CL_QUEUE_CONTEXT`	Return type: cl_context Return the context specified when the command-queue is created.
`CL_QUEUE_DEVICE`	Return type: cl_device_id Return the device specified when the command-queue is created.
`CL_QUEUE_REFERENCE_COUNT`	Return type: cl_uint Return the command-queue reference count. The reference count returned with `CL_QUEUE_REFERENCE_COUNT` should be considered immediately stale. It is unsuitable for general use in applications. This feature is provided for identifying memory leaks.
`CL_QUEUE_PROPERTIES`	Return type: cl_command_queue_properties Return the currently specified properties for the command-queue. These properties are specified by the value associated with the `CL_COMMAND_QUEUE_PROPERTIES` passed in `properties` argument in clCreateCommandQueueWithProperties.
`CL_QUEUE_SIZE`	Return type: cl_uint Return the currently specified size for the device command-queue. This query is only supported for device command queues.

Notes

It is possible that a device(s) becomes unavailable after a context and command-queues that use this device(s) have been created and commands have been queued to command-queues. In this case the behavior of OpenCL API calls that use this context (and command-queues) are considered to be implementation-defined. The user callback function, if specified, when the context is created can be used to record appropriate information in the errinfo, private_info arguments passed to the callback function when the device becomes unavailable.

Errors

Returns CL_SUCCESS if the function is executed successfully. Otherwise, it returns one of the following errors:

Returns CL_INVALID_COMMAND_QUEUE if command_queue is not a valid command-queue.
Returns CL_INVALID_VALUE if param_name is not one of the supported values or if size in bytes specified by param_value_size is less than size of return type and param_value is not a NULL value.
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

clCreateCommandQueueWithProperties, clReleaseCommandQueue, clRetainCommandQueue

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