VecStashSetInitialSize#

sets the sizes of the vec-stash, that is used during the assembly process to store values that belong to other processors.

Synopsis#

#include "petscvec.h"   
PetscErrorCode VecStashSetInitialSize(Vec vec, PetscInt size, PetscInt bsize)

Not Collective, different processes can have different size stashes

Input Parameters#

vec - the vector
size - the initial size of the stash.
bsize - the initial size of the block-stash(if used).

Options Database Keys#

-vecstash_initial_size or <size0,size1,…sizep- 1>
-vecstash_block_initial_size or <bsize0,bsize1,…bsizep- 1>

Notes#

The block-stash is used for values set with VecSetValuesBlocked() while the stash is used for values set with VecSetValues()

Run with the option -info and look for output of the form VecAssemblyBegin_MPIXXX:Stash has MM entries, uses nn mallocs. to determine the appropriate value, MM, to use for size and VecAssemblyBegin_MPIXXX:Block-Stash has BMM entries, uses nn mallocs. to determine the value, BMM to use for bsize

PETSc attempts to smartly manage the stash size so there is little likelihood setting a a specific value here will affect performance