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

[Pavan Balaji]

No.  Think of hydra as an ssh program.  If you run mpiexec as root, 
it'll try to ssh as root.  You'll need to make sure ssh as root is 
passwordless.

  -- Pavan

On 06/13/2013 10:08 AM, Lee, Eibhlin wrote:
> My apologies,
> So hydra is in effect a super user?
> Eibhlin
> ________________________________________
> From: Pavan Balaji [balaji at mcs.anl.gov]
> Sent: 13 June 2013 16:02
> To: Lee, Eibhlin
> Cc: discuss at mpich.org
> Subject: Re: [mpich-discuss] Running an mpi program that needs to access /dev/mem
>
> 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
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> discuss mailing list     discuss at mpich.org
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>>>>>
>>>>
>>>
>>> --
>>> Pavan Balaji
>>> http://www.mcs.anl.gov/~balaji
>>> _______________________________________________
>>> discuss mailing list     discuss at mpich.org
>>> To manage subscription options or unsubscribe:
>>> https://lists.mpich.org/mailman/listinfo/discuss
>>> _______________________________________________
>>> discuss mailing list     discuss at mpich.org
>>> To manage subscription options or unsubscribe:
>>> https://lists.mpich.org/mailman/listinfo/discuss
>>>
>>
>> --
>> Pavan Balaji
>> http://www.mcs.anl.gov/~balaji
>>
>
> --
> Pavan Balaji
> http://www.mcs.anl.gov/~balaji
>

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