KSPGMRESSetPreAllocateVectors#
Causes KSPGMRES and KSPFGMRES to preallocate all its needed work vectors at initial setup rather than the default, which is to allocate several at a time when needed.
Synopsis#
#include "petscksp.h"
PetscErrorCode KSPGMRESSetPreAllocateVectors(KSP ksp)
Logically Collective
Input Parameter#
ksp - iterative context obtained from
KSPCreate()
Options Database Key#
-ksp_gmres_preallocate - Activates
KSPGmresSetPreAllocateVectors()
Notes#
If one knows the number of iterations will be greater than or equal to the KSPGMRESSetRestart() size then calling
this routine can result in faster performance since it minimizes the number of separate memory allocations used
and can improve the performance of VecMDot() and VecMAXPY() which may utilize BLAS 2 operations that benefit from
the larger allocations.
Using this function with vectors in GPU memory may waste GPU memory if not all the restart directions are used in solving the system, that is the solver converges before the number of iterations reaches the restart value.
See Also#
KSP: Linear System Solvers, KSPGMRESSetRestart(), KSPGMRESSetOrthogonalization(), KSPGMRESGetOrthogonalization(),
VecMDot(), VecMAXPY()
Level#
intermediate
Location#
Implementations#
KSPGMRESSetPreAllocateVectors_GMRES() in src/ksp/ksp/impls/gmres/gmres.c
Index of all KSP routines
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Index of all manual pages