examples-mpi/README.md

# mpi !

Instances of Ubuntu Linux with [MPICH](https://www.mpich.org) -- portable implementation of Message Passing Interface (MPI) standard. Designed for MPI program development and deployment.

##  LabInstance mpi


![alt text](images/swarmlab-network.png "")




[inspired by NLKNguyen](https://github.com/NLKNguyen/alpine-mpich)


## Quickstart

This is a quickstart guide of howto use this *LabInstance to deploy MPI programs*

### HowTo use it


- On step "*1. Select Git Repo*" [see here](http://docs.swarmlab.io/SwarmLab-HowTos/HowTo-create-lab.adoc.html) 
choose "*examples-mpi*" 

- On step "*2. Select swarm service*" choose "*ondemand_mpi_master*"

- On step "*3. Save Lab Instance*" put the name you want

- Save it. 

Your are ready to run your fresh *LabInstance* [see here](http://docs.swarmlab.io/SwarmLab-HowTos/HowTo-create-lab.adoc.html#_run_instance)
  

### Default Configuration 

- Working Directory

> /project

- Default user for MPI

> mpi

- Buid-in Web Server
 
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**INFO**

*Lab_Instance Name* = The name you give [here](http://docs.swarmlab.io/SwarmLab-HowTos/HowTo-create-lab.adoc.html#_step_3_save_lab_instance)

You can also find [here](http://docs.swarmlab.io/SwarmLab-HowTos/index.adoc.html#_main_lab_intance_interface)

Usage: 

> touch /var/www/html/[name]/file

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- The host file that contains addresses of connected workers can be created with:

> IP_ADDR=$(ip addr show | grep "inet " | grep  "eth0" | awk '{print $2}')
>
> nmap -sP $IP_ADDR  | grep ondemand_mpi_worker | awk  -F "[()]" '{ for (i=2; i<NF; i+=2) print $i }' > /project/hosts

- Compile

> mpicc -o /project/mpi_hello_world examples/mpi_hello_world.c

- run the MPI hello world program

> sudo -u mpi mpirun -n 10 -f /project/hosts  /project/mpi_hello_world


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**NOTE:** copy hello world to all clients

```bash
# scp hello wrold to all clients. sudo -u mpi for auto scp connect. see /home/mpi/.ssh 
while read -r line; 
 do 
   sudo -u mpi scp /project/mpi_hello_world mpi@$line:/project/mpi_hello_world
done < /project/hosts
```
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**MORE INFO** 

See swarmlab and examples directory
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