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GPU
,→The SIMT Programming Model
Once doA() is complete, the machine will continue and doB(). In this case, thread#0 will have its execution mask-cleared, while threads #1 through #31 will actually complete the results of doB().
This highlights the fundamental trade off of the GPU platform. GPUs have many threads of execution, but they are forced to execute with their warps or wavefronts. In complicated loops or trees of if-statements, this thread divergence problem can cause your code to potentially leave many hardware threads idle. In the above example code, 97% of the threads will be effectively idle during doA(), while 3% of the threads will be idle during doB().
== Blocks and Workgroups ==
