Figure 5. Workflow in the MCMC kernel.

(a) Workflow for a single iteration and a single parameter update describing how computation tasks are distributed between the threads of a block () in a case with gradient directions. The calculation of the model-predicted signals for the different gradient directions is distributed as evenly as possible between threads within a thread block. The remaining tasks, which are not computationally demanding, are performed by a leader thread, while the rest of threads are waiting. (b) Workflow for a thread block of the MCMC kernel that performs all T iterations for all R parameters (i.e. for a voxel). Each block has threads. The threads need to be synchronised at certain steps.