Block Format Keyword Sets SPMD parameters for Hybrid Massively Parallel Program (HMPP) computation.


(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
Domdec Nspmd   Dkword   Nthread        


Field Contents SI Unit Example
Domdec Type of domain decomposition for SPMD version
= 0 (Default)
Set to 3.
Set to 5, if /IMPLICIT is defined.
= 2
RSB (Recursive Symmetric Bisection) decomposition.
= 3
Multilevel Kway decomposition.
= 5
Multilevel Kway decomposition based on DOF.


Nspmd Number of SPMD domains.

Default set to 1 (Integer)

Dkword User-defined value for requested memory used by RSB Domain Decomposition

Default value is computed by Radioss Starter.


Nthread Number of SMP threads per SPMD domain

Default set to 1 (Integer)



  1. Recursive Symmetric Bisection (RSB) is a domain decomposition method based on the public domain algorithm called "Recursive Spectral Decomposition". For performance reasons, it is highly recommended to use the multilevel Kway decomposition instead of RSB.
  2. Multilevel Kway is a domain decomposition method based on Metis multilevel Kway algorithm. This algorithm is advised in order to enhance performance in case of complex contact interfaces and for Fluid Structure Interaction problems that involve both Lagrangian and ALE formulations.
  3. Multilevel Kway domain decomposition based on DOF is suitable if /DT/AMS or implicit application is invoked by Radioss Engine. It optimizes decomposition taking into account DOF.
  4. Dkword definition is only required when the default value for RSB is not high enough.
  5. With the HMPP version, the total number of processes is equal to Nspmd x Nthread. More precisely, each Nspmd distributed parallel program is composed of Nthread SMP threads. It is also possible to set Nspmd and Nthread using Run Executables Directly options.
  6. When using /DT/AMS in Radioss Engine, it is recommended to set Domdec to 5 in /SPMD from Radioss Starter (for versions 11.0.230 and above, set to 0 and Radioss automatically applies the relevant Domdec option.)
  7. PARITH/ON is not yet available with AMS, if the number of domains changes, but for the same domain number, the results are the same whatever the number of threads.