Table 4.

Performance measurements of coupled simulations which consist of HemeLB running on HECToR and pyNS running on a local UCL workstation. The type of simulation, single-scale (ss) or coupled multiscale (ms) is given in the first columns. The number of cores used by HemeLB and the initialization time are, respectively, given in the second and third column. The time spent on HemeLB and coupling work are given, respectively, in the fourth and fifth column, the total time in the sixth column and the efficiency in the seventh column. The times for HemeLB model execution in the multiscale runs are estimates, which we derived directly from the single-scale performance results of the same problem on the same resources.

ss/ms	cores	init (time spent)	HemeLB* (time spent)	coupling (time spent)	total (time spent)	coupling efficiency
ss	512	47.9	2223	n.a.	2271	n.a.
ms	512	51.2	2223	24	2298	98.8%
ss	2048	46.4	815	n.a.	862	n.a.
ms	2048	50.5	815	37	907	95.0%