[mpich-discuss] modifying the round-robin

[Ralph Butler]

With the correct set of cmd-line options, you can accomplish lots of  
scenarios.  But, it may make for some
long cmd lines.  I have a set of machines named bp400-bp415 in an mpd  
ring.  I can use the -machinefile
option to mpiexec to map processes to hosts.  For example, below is a  
demo where I want to run 4 processes
and I want the first 2 to run on bp402 and the next 2 to run on bp404.
--ralph

(bp400:56)% cat tempmf
bp402:2
bp404:2
(bp400:57)% mpiexec -l -machinefile tempmf -n 4 hostname   |   sort
0: bp402
1: bp402
2: bp404
3: bp404


On ThuDec 11, at Thu Dec 11 6:41AM, Benjamin Svetitsky wrote:

> Thanks, the -1 option indeed gets all 4 processes to run on nodeB.   
> But then if I start another -n 4 job, it goes to nodeB as well.  Is  
> there a way to get mpd to do load balancing here (namely to send all  
> 4 to the next node in line) without specifying the node in the  
> mpiexec command?
>
> 		Ben
>
> Rajeev Thakur wrote:
>> Since you are running from node C, MPD will place the first process  
>> on node
>> C by default. You can turn that feature off with the "-1" option to  
>> mpiexec.
>> Rajeev
>>> -----Original Message-----
>>> From: mpich-discuss-bounces at mcs.anl.gov [mailto:mpich-discuss-bounces at mcs.anl.gov 
>>> ] On Behalf Of Benjamin Svetitsky
>>> Sent: Wednesday, December 10, 2008 2:41 AM
>>> To: mpich-discuss at mcs.anl.gov
>>> Subject: [mpich-discuss] modifying the round-robin
>>>
>>> Greetings,
>>>
>>> I am running MPICH2 on a cluster of four quad-core machines under  
>>> Linux.   If I run a job such as
>>>
>>> mpiexec -l -n 4 hostname
>>>
>>> then one process runs on each node, whereas I would prefer that  
>>> all four run on the same node.  I tried modifying mpd.hosts to read:
>>>
>>> nodeA:4
>>> nodeB:4
>>> nodeC:4
>>> nodeD:4
>>>
>>> but the result is not what I expected:
>>>
>>> nodeC% mpiexec -l -n 4 hostname
>>> 0: nodeC
>>> 3: nodeB
>>> 2: nodeB
>>> 1: nodeB
>>>
>>> How can I get the mpd to fill the hosts one by one reliably?
>>>
>>> Incidentally, the :4 option is not documented in the Installation  
>>> Guide.   I picked it up in the gutter.  If it doesn't do this,  
>>> what DOES it do?
>>>
>>> Thanks,
>>> 	Ben
>>> -- 
>>> Prof. Benjamin Svetitsky         Phone:            +972-3-640 8870
>>> School of Physics and Astronomy  Fax:              +972-3-640 7932
>>> Tel Aviv University              E-mail:      bqs at julian.tau.ac.il
>>> 69978 Tel Aviv, Israel           WWW: http://julian.tau.ac.il/~bqs
>>>
>
> -- 
> Prof. Benjamin Svetitsky         Phone:            +972-3-640 8870
> School of Physics and Astronomy  Fax:              +972-3-640 7932
> Tel Aviv University              E-mail:      bqs at julian.tau.ac.il
> 69978 Tel Aviv, Israel           WWW: http://julian.tau.ac.il/~bqs