Initializes a generalized scatter from one vector to another for GPU based computation.
PETSC_EXTERN PetscErrorCode VecScatterInitializeForGPU(VecScatter inctx,Vec x)
|inctx ||- scatter context generated by VecScatterCreate()
|x ||- the vector from which we scatter
Effectively, this function creates all the necessary indexing buffers and work
vectors needed to move only those data points in a vector which need to
be communicated across ranks. This is done at the first time this function is
called. Currently, this only used in the context of the parallel SpMV call in
This function is executed before the call to MatMult. This enables the memory
transfers to be overlapped with the MatMult SpMV kernel call.
VecScatterFinalizeForGPU(), VecScatterCreate(), VecScatterEnd()