[petsc-users] reusing matrix created with MatCreateMPIAIJWithSplitArrays

[Hassan Raiesi]

Hello,

We are using PETSC in our CFD code, and  noticed that using "MatCreateMPIAIJWithSplitArrays" is almost 60% faster for large problem size (i.e DOF > 725M, using GAMG each time-step only takes 5sec, compared to 8.3 sec when assembling the matrix one row at a time using matsetvaluesblocked()  as recommended).

The problem is that the memory usage goes up after each call to MatCreateMPIAIJWithSplitArrays  to update the matrix values. As MatCreateMPIAIJWithSplitArrays is not supposed to copy the values, do we need to call it each time to update the values? We tried to just update the values of the diagonal and off-diagonal part of the arrays passed to "MatCreateMPIAIJWithSplitArrays", (the sparsity structure is fixed) but it looks like that the values are not updated, what is the proper way to update the values of the matrix created by MatCreateMPIAIJWithSplitArrays?


Thank you

Hassan Raiesi,


Advanced Aerodynamics Department

Bombardier Aerospace


hassan.raiesi at aero.bombardier.com



2351 boul. Alfred-Nobel (BAN1)

Ville Saint-Laurent, Québec, H4S 2A9






Tél.

  514-855-5001    # 62204





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