get_num_sub_groups

Returns the number of subgroups that the current workgroup is divided into.

uint get_num_sub_groups ()

Description

Returns the number of subgroups that the current workgroup is divided into. This number will be constant for the duration of a workgroup’s execution. If the kernel is executed with a non-uniform work-group size (i.e. the global_work_size values specified to clEnqueueNDRangeKernel are not evenly divisable by the local_work_size values for each dimension) values for any dimension, calls to this built-in from some work-groups may return different values than calls to this built-in from other work-groups.

Specification

OpenCL Specification

Also see

cl_khr_subgroups

Copyright © 2007-2013 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.