[mpich-discuss] Running an mpi program that needs to access /dev/mem

[Gus Correa]

Hi Lee

How about replacing "~/main" in the mpiexec command line
by one-liner script?
Say, "sudo_main.sh", something like this:

#! /bin/bash
sudo ~/main

After all, it is "main" that accesses /dev/mem,
and needs "sudo" permissions, not mpiexec, right?
[Or do the mpiexec-launched processes inherit
the "sudo" stuff from mpiexec?]

Not related, but, instead of putting mpiexec in /usr/bin,
can't you just use the full path to it?

I hope this helps,
Gus Correa

On 06/13/2013 10:09 AM, Lee, Eibhlin wrote:
> Pavan,
> I had a lot of trouble getting hydra to work without having to enter a password/passphrase. I saw the option to pass a phrase in the mpich installers guide. I eventually found that for that command you needed to use the smpd process manager. That's the only reason I chose smpd over hydra.
> As to your other suggestion. I ran ./main and the same error (Can't open /dev/mem...) appeared. sudo ./main works but of course without multiple processes.
> Eibhlin
> ________________________________________
> From: discuss-bounces at mpich.org [discuss-bounces at mpich.org] on behalf of Pavan Balaji [balaji at mcs.anl.gov]
> Sent: 13 June 2013 14:34
> To: discuss at mpich.org
> Subject: Re: [mpich-discuss] Running an mpi program that needs to access        /dev/mem
>
> I just saw your older email.  Why are you using smpd instead of the
> default process manager (hydra)?
>
>    -- Pavan
>
> On 06/13/2013 08:05 AM, Pavan Balaji wrote:
>>
>> What's "-phrase"?  That's not a recognized option.  I'm not sure where
>> the /dev/mem check is coming from.  Try running ~/main without mpiexec
>> first.
>>
>>    -- Pavan
>>
>> On 06/13/2013 06:56 AM, Lee, Eibhlin wrote:
>>> Hello all,
>>>
>>> I am trying to use two raspberry-pi to sample and then process some
>>> data. The first process samples while the second processes and vice
>>> versa. To do this I use gpio and also mpich-3.0.4 with the process
>>> manager smpd. I have successfully run cpi on both machines (from the
>>> master machine). I have also managed to run a similar program but
>>> without the MPI, this involved compiling with gcc and when running
>>> putting sudo in front of the binary file.
>>>
>>> When I combine these two processes I get various error messages.
>>> For input:
>>> mpiexec -phrase cat -machinefile machinefile -n 2 ~/main
>>> the error is:
>>> Can't open /dev/mem
>>> Did you forget to use 'sudo .. ?'
>>>
>>> For input:
>>> sudo mpiexec -phrase cat -machinefile machinefile -n 2 ~/main
>>> the error is:
>>> sudo: mpiexec: Command not found
>>>
>>> I therefore put mpiexec into /usr/bin
>>>
>>> now for input:
>>> sudo mpiexec -phrase cat -machinefile machinefile -n 2 ~/main
>>> the error is:
>>> Can't open /dev/mem
>>> Did you forget to use 'sudo .. ?'
>>>
>>> Does anyone know how I can work around this?
>>> Thanks,
>>> Eibhlin
>>>
>>>
>>>
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>>
>
> --
> Pavan Balaji
> http://www.mcs.anl.gov/~balaji
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