# DMSwarmGetSize
Retrieves the total length of fields registered 
## Synopsis
```
#include "petscdmswarm.h"   
PetscErrorCode DMSwarmGetSize(DM dm, PetscInt *n)
```
Collective on dm


## Input parameter

- ***dm -*** a DMSwarm



## Output parameter

- ***n -*** the total length of each registered field





## Note
This calls MPI_Allreduce upon each call (inefficient but safe)


## See Also
 `DMSwarmGetLocalSize()`, `DMSwarmSetLocalSizes()`

## Level
beginner

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/swarm/swarm.c.html#DMSwarmGetSize">src/dm/impls/swarm/swarm.c</A>

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/tutorials/swarm_ex1.c.html">src/dm/tutorials/swarm_ex1.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ts/tutorials/ex77.c.html">src/ts/tutorials/ex77.c.html</A><BR>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/dm/impls/swarm/swarm.c)


[Index of all DMSwarm routines](index.md)  
[Table of Contents for all manual pages](/docs/manualpages/index.md)  
[Index of all manual pages](/docs/manualpages/singleindex.md)