[petsc-users] Call to DMSetMatrixPreallocateSkip not changing allocation behavior

[Fackler, Philip via petsc-users]

I'm using the following sequence of functions related to the Jacobian matrix:

DMDACreate1d(..., &da);
DMSetFromOptions(da);
DMSetUp(da);
DMSetMatType(da, MATAIJKOKKOS);
DMSetMatrixPreallocateSkip(da, PETSC_TRUE);
Mat J;
DMCreateMatrix(da, &J);
MatSetPreallocationCOO(J, ...);

I recently added the call to DMSetMatrixPreallocateSkip, hoping the allocation 
would be delayed to MatSetPreallocationCOO, and that it would require less 
memory. The 
documentation<https://petsc.org/release/manualpages/DM/DMSetMatrixPreallocateSkip/>
 says that the data structures will not be preallocated. The following data 
from heaptrack shows that the allocation is still happening in the call to 
DMCreateMatrix.

[cid:bda9ef12-a46f-47b2-9b9b-a4b2808b6b13]

Can someone help me understand this?

Thanks,

Philip Fackler
Research Software Engineer, Application Engineering Group
Advanced Computing Systems Research Section
Computer Science and Mathematics Division
Oak Ridge National Laboratory