Provided by: opencl-1.2-man-doc_1.0~svn27110-1_all 
NAME
clGetKernelWorkGroupInfo - Returns information about the kernel object that may be
specific to a device.
cl_int clGetKernelWorkGroupInfo(cl_kernel kernel, cl_device_id device,
cl_kernel_work_group_info param_name,
size_t param_value_size, void *param_value,
size_t *param_value_size_ret);
PARAMETERS
kernel
Specifies the kernel object being queried.
device
Identifies a specific device in the list of devices associated with kernel. The list
of devices is the list of devices in the OpenCL context that is associated with
kernel. If the list of devices associated with kernel is a single device, device can
be a NULL value.
param_name
Specifies the information to query. The list of supported param_name types and the
information returned in param_value by clGetKernelWorkGroupInfo is described in the
table below.
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
Used to specify 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.
┌───────────────────────────┬─────────────┬────────────────────────────────────────┐
│cl_kernel_work_group_info │ Return Type │ Info. returned in │
│ │ │ param_value │
├───────────────────────────┼─────────────┼────────────────────────────────────────┤
│CL_KERNEL_GLOBAL_WORK_SIZE │ size_t[3] │ This provides a │
│ │ │ mechanism for the │
│ │ │ application to query the │
│ │ │ maximum global size that │
│ │ │ can be used to execute a │
│ │ │ kernel (i.e. │
│ │ │ global_work_size │
│ │ │ argument to │
│ │ │ clEnqueueNDRangeKernel(3clc)) │
│ │ │ on a custom device given │
│ │ │ by device or a built-in │
│ │ │ kernel on an OpenCL │
│ │ │ device given by device. │
│ │ │ │
│ │ │ If device is not a │
│ │ │ custom device or kernel │
│ │ │ is not a built-in │
│ │ │ kernel, │
│ │ │ clGetKernelArgInfo(3clc) │
│ │ │ returns the error │
│ │ │ CL_INVALID_VALUE. │
├───────────────────────────┼─────────────┼────────────────────────────────────────┤
│CL_KERNEL_WORK_GROUP_SIZE │ size_t │ This provides a mechanism for │
│ │ │ the application to query the │
│ │ │ maximum work-group size that │
│ │ │ can be used to execute a │
│ │ │ kernel on a specific device │
│ │ │ given by device. The OpenCL │
│ │ │ implementation uses the │
│ │ │ resource requirements of the │
│ │ │ kernel (register usage etc.) │
│ │ │ to determine what this │
│ │ │ work-group size should be. │
├───────────────────────────┼─────────────┼────────────────────────────────────────┤
│CL_KERNEL_COMPILE_- │ size_t[3] │ Returns the work-group size │
│WORK_GROUP_SIZE │ │ specified by the │
│ │ │ __attribute__((reqd_work_group_size(X, │
│ │ │ Y, Z))) qualifier. See │
│ │ │ functionQualifiers(3clc). If │
│ │ │ the work-group size is not │
│ │ │ specified using the above │
│ │ │ attribute qualifier (0, 0, 0) │
│ │ │ is returned. │
├───────────────────────────┼─────────────┼────────────────────────────────────────┤
│CL_KERNEL_LOCAL_MEM_SIZE │ cl_ulong │ Returns the amount of local memory in │
│ │ │ bytes being used by a kernel. This │
│ │ │ includes local memory that may be │
│ │ │ needed by an implementation to execute │
│ │ │ the kernel, variables declared inside │
│ │ │ the kernel with the local(3clc) │
│ │ │ address qualifier and local memory to │
│ │ │ be allocated for arguments to the │
│ │ │ kernel declared as pointers with the │
│ │ │ local(3clc) address qualifier and │
│ │ │ whose size is specified with │
│ │ │ clSetKernelArg(3clc). │
│ │ │ │
│ │ │ If the local memory size, for any │
│ │ │ pointer argument to the kernel │
│ │ │ declared with the local(3clc) address │
│ │ │ qualifier, is not specified, its size │
│ │ │ is assumed to be 0. │
├───────────────────────────┼─────────────┼────────────────────────────────────────┤
│CL_KERNEL_PREFERRED_WORK_- │ size_t │ Returns the preferred multiple of │
│GROUP_SIZE_MULTIPLE │ │ workgroup size for launch. This is a │
│ │ │ performance hint. Specifying a │
│ │ │ workgroup size that is not a multiple │
│ │ │ of the value returned by this query as │
│ │ │ the value of the local work size │
│ │ │ argument to │
│ │ │ clEnqueueNDRangeKernel(3clc)will not │
│ │ │ fail to enqueue the kernel for │
│ │ │ execution unless the work-group size │
│ │ │ specified is larger than the device │
│ │ │ maximum. │
├───────────────────────────┼─────────────┼────────────────────────────────────────┤
│CL_KERNEL_PRIVATE_MEM_SIZE │ cl_ulong │ Returns the minimum amount of private │
│ │ │ memory, in bytes, used by each │
│ │ │ workitem in the kernel. This value may │
│ │ │ include any private memory needed by │
│ │ │ an implementation to execute the │
│ │ │ kernel, including that used by the │
│ │ │ language built-ins and variable │
│ │ │ declared inside the kernel with the │
│ │ │ private(3clc) qualifier. │
└───────────────────────────┴─────────────┴────────────────────────────────────────┘
param_value_size_ret
Returns the actual size in bytes of data copied to param_value. If
param_value_size_ret is NULL, it is ignored.
ERRORS
Returns CL_SUCCESS if the function is executed successfully. Otherwise, it returns one of
the following errors:
• CL_INVALID_DEVICE if device is not in the list of devices associated with kernel or if
device is NULL but there is more than one device associated with kernel.
• CL_INVALID_VALUE if param_name is not valid, or if size in bytes specified by
param_value_size is < size of return type as described in the table above and
param_value is not NULL.
• CL_INVALID_VALUE if param_name is CL_KERNEL_GLOBAL_WORK_SIZE and device is not a
custom device or kernel is not a built-in kernel.
• CL_INVALID_KERNEL if kernel is a not a valid kernel object.
• 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[1]
SEE ALSO
clCreateKernel(3clc), clCreateKernelsInProgram(3clc), clReleaseKernel(3clc),
clRetainKernel(3clc), clSetKernelArg(3clc), clGetKernelInfo(3clc)
AUTHORS
The Khronos Group
COPYRIGHT
Copyright © 2007-2011 The Khronos Group Inc.
Permission is hereby granted, free of charge, to any person obtaining a copy of this
software and/or associated documentation files (the "Materials"), to deal in the Materials
without restriction, including without limitation the rights to use, copy, modify, merge,
publish, distribute, sublicense, and/or sell copies of the Materials, and to permit
persons to whom the Materials are furnished to do so, subject to the condition that this
copyright notice and permission notice shall be included in all copies or substantial
portions of the Materials.
NOTES
1. OpenCL Specification
page 164, section 5.7.3 - Kernel Object Queries