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

[Pavan Balaji]

Please don't drop the mailing list from the cc.

You can do an strace to see where /dev/mem is being used.

If you are using multiple nodes, hydra only relies on passwordless ssh. 
  It doesn't really care what the user id is (root or non-root).

  -- Pavan

On 06/13/2013 09:27 AM, Lee, Eibhlin wrote:
> Unfortunately I didn't come across this mailing list until recently. Sods law.
> ./main does not work but sudo ./main does work.
> Could hydra compile and run a program where this is the case?
> I ask because the only way I'll be able to get around using sudo is to change ownership of /dev/mem. It goes without saying that that's dangerous!
> Eibhlin
> ________________________________________
> From: Pavan Balaji [balaji at mcs.anl.gov]
> Sent: 13 June 2013 15:21
> To: discuss at mpich.org
> Cc: Lee, Eibhlin
> Subject: Re: [mpich-discuss] Running an mpi program that needs to access        /dev/mem
>
> smpd was mainly meant for windows support.  It is now deprecated, so we
> don't officially support that.  Someone on the mailing list might help,
> but no promises.
>
> With respect to hydra, problems with that is what you should have
> reported on this mailing list and we would have tried to help.  :-)
>
> If ./main itself is not working, there's no hope of getting it to work
> with mpiexec.  You'll need to debug that first.
>
>    -- Pavan
>
> On 06/13/2013 09:09 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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>
> --
> Pavan Balaji
> http://www.mcs.anl.gov/~balaji
>

-- 
Pavan Balaji
http://www.mcs.anl.gov/~balaji