:orphan:
# PetscSFWindowSetFlavorType
Set flavor type for `MPI_Win` creation 
## Synopsis
```
#include "petscsf.h" 
PetscErrorCode PetscSFWindowSetFlavorType(PetscSF sf, PetscSFWindowFlavorType flavor)
```
Logically Collective


## Input Parameters

- ***sf -*** star forest for communication of type `PETSCSFWINDOW`
- ***flavor -*** flavor type



## Options Database Key

- ***-sf_window_flavor <flavor> -*** sets the flavor type CREATE, DYNAMIC, ALLOCATE or SHARED (see `PetscSFWindowFlavorType`)





## Notes

## Windows reuse follows these rules
```none
     PETSCSF_WINDOW_FLAVOR_CREATE: creates a new window every time, uses MPI_Win_create

     PETSCSF_WINDOW_FLAVOR_DYNAMIC: uses MPI_Win_create_dynamic/MPI_Win_attach and tries to reuse windows by comparing the root array. Intended to be used on repeated applications of the same SF, e.g.
       for i=1 to K
         PetscSFOperationBegin(rootdata1,leafdata_whatever);
         PetscSFOperationEnd(rootdata1,leafdata_whatever);
         ...
         PetscSFOperationBegin(rootdataN,leafdata_whatever);
         PetscSFOperationEnd(rootdataN,leafdata_whatever);
       endfor
       The following pattern will instead raise an error
         PetscSFOperationBegin(rootdata1,leafdata_whatever);
         PetscSFOperationEnd(rootdata1,leafdata_whatever);
         PetscSFOperationBegin(rank ? rootdata1 : rootdata2,leafdata_whatever);
         PetscSFOperationEnd(rank ? rootdata1 : rootdata2,leafdata_whatever);

     PETSCSF_WINDOW_FLAVOR_ALLOCATE: uses MPI_Win_allocate, reuses any pre-existing window which fits the data and it is not in use

     PETSCSF_WINDOW_FLAVOR_SHARED: uses MPI_Win_allocate_shared, reusage policy as for PETSCSF_WINDOW_FLAVOR_ALLOCATE
```



## See Also
  `PetscSF`, `PETSCSFWINDOW`, `PetscSFSetFromOptions()`, `PetscSFWindowGetFlavorType()`

## Level
advanced

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/is/sf/impls/window/sfwindow.c.html#PetscSFWindowSetFlavorType">src/vec/is/sf/impls/window/sfwindow.c</A>

## Implementations

<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/vec/is/sf/impls/window/sfwindow.c.html#PetscSFWindowSetFlavorType_Window">PetscSFWindowSetFlavorType_Window in src/vec/is/sf/impls/window/sfwindow.c</A><BR>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/vec/is/sf/impls/window/sfwindow.c)


[Index of all PetscSF routines](index.md)  
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