Using MPI with two RaspberryPi

Question

I am trying to make a 'dual core' RaspberryPi for a project I am working on. I had followed this tutorial by Simon Cox. Unfortunately I could not get the two RasPi to talk to each other. (This was using Hydra as the process manager)

After looking more carefully at the MPICH installers guide, which can be found here, I tried to use the -phrase to pass the passphrase I had created. However I could not find it as part of the hydra commands. So I re-installed with smpd and after many compiling attempts. I configured with:

/configure -prefix=/home/pi/mpich-install --with-pm=smpd --with-pmi=smpd

I also had to install libbsl-dev to get the MD5 that smpd requires. I also exported the path that the commands mpiexec and mpicc are in. After setting the passphrase I copied the image to a second SD card and put it in a second RasPi. I then set up the passphrase using ssh-keygen.

I was able to run the cpi program on the master Pi and the slave Pi individually but when I tried to run multiple processes on both at the same time I got the error

Fatal error in MPI_Init: Other MPI error, error stack: MPIR_Init``_thread(392).................: MPID_Init(139)........................: channel initialization failed MPIDI_CH3_Init(38)....................: MPID_nem_init(196)....................: MPIDI_CH3I_Seg_commit(366)............: MPIU_SHMW_Hnd_deserialize(324)........: MPIU_SHMW_Seg_open(863)...............: MPIU_SHMW_Seg_create_attach_templ(637): open failed - No such file or directory

Can someone please suggest how I can either fix this problem or get the RaspberryPis to communicate using MPICH?

Thanks E.Lee

Answer 1

If anyone else has this problem make sure your hosts don't have the same name! You can change it by following this tutorial http://raspi.tv/2012/how-to-change-the-name-of-your-raspberry-pi-new-hostname