1 #include <../src/ksp/ksp/impls/gmres/gmresimpl.h> /*I "petscksp.h" I*/
2
3 /*@
4 KSPGMRESSetPreAllocateVectors - Causes `KSPGMRES` and `KSPFGMRES` to preallocate all its
5 needed work vectors at initial setup rather than the default, which
6 is to allocate several at a time when needed.
7
8 Logically Collective
9
10 Input Parameter:
11 . ksp - iterative context obtained from `KSPCreate()`
12
13 Options Database Key:
14 . -ksp_gmres_preallocate - Activates `KSPGmresSetPreAllocateVectors()`
15
16 Level: intermediate
17
18 Notes:
19 If one knows the number of iterations will be greater than or equal to the `KSPGMRESSetRestart()` size then calling
20 this routine can result in faster performance since it minimizes the number of separate memory allocations used
21 and can improve the performance of `VecMDot()` and `VecMAXPY()` which may utilize BLAS 2 operations that benefit from
22 the larger allocations.
23
24 Using this function with vectors in GPU memory may waste GPU memory if not all the restart directions are used in solving the system,
25 that is the solver converges before the number of iterations reaches the restart value.
26
27 .seealso: [](ch_ksp), `KSPGMRESSetRestart()`, `KSPGMRESSetOrthogonalization()`, `KSPGMRESGetOrthogonalization()`,
28 `VecMDot()`, `VecMAXPY()`
29 @*/
KSPGMRESSetPreAllocateVectors(KSP ksp)30 PetscErrorCode KSPGMRESSetPreAllocateVectors(KSP ksp)
31 {
32 PetscFunctionBegin;
33 PetscTryMethod(ksp, "KSPGMRESSetPreAllocateVectors_C", (KSP), (ksp));
34 PetscFunctionReturn(PETSC_SUCCESS);
35 }
36