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Subject: Re: [OMPI users] MPI process dies with a route error when using dynamic process calls to connect more than 2 clients to a server with InfiniBand
From: Philippe (philmpi_at_[hidden])
Date: 2010-08-23 15:15:10


I took a look at the code but I'm afraid I dont see anything wrong.

p.

On Thu, Aug 19, 2010 at 2:32 PM, Ralph Castain <rhc_at_[hidden]> wrote:
> Yes, that is correct - we reserve the first port in the range for a daemon,
> should one exist.
> The problem is clearly that get_node_rank is returning the wrong value for
> the second process (your rank=1). If you want to dig deeper, look at the
> orte/mca/ess/generic code where it generates the nidmap and pidmap. There is
> a bug down there somewhere that gives the wrong answer when ppn > 1.
>
>
> On Thu, Aug 19, 2010 at 12:12 PM, Philippe <philmpi_at_[hidden]> wrote:
>>
>> Ralph,
>>
>> somewhere in ./orte/mca/oob/tcp/oob_tcp.c, there is this comment:
>>
>>                orte_node_rank_t nrank;
>>                /* do I know my node_local_rank yet? */
>>                if (ORTE_NODE_RANK_INVALID != (nrank =
>> orte_ess.get_node_rank(ORTE_PROC_MY_NAME)) &&
>>                    (nrank+1) <
>> opal_argv_count(mca_oob_tcp_component.tcp4_static_ports)) {
>>                    /* any daemon takes the first entry, so we start
>> with the second */
>>
>> which seems constant with process #0 listening on 10001. the question
>> would be why process #1 attempt to connect to port 10000 then? or
>> maybe totally unrelated :-)
>>
>> btw, if I trick process #1 to open the connection to 10001 by shifting
>> the range, I now get this error and the process terminate immediately:
>>
>> [c0301b10e1:03919] [[0,9999],1]-[[0,0],0]
>> mca_oob_tcp_peer_recv_connect_ack: received unexpected process
>> identifier [[0,9999],0]
>>
>> good luck with the surgery and wishing you a prompt recovery!
>>
>> p.
>>
>> On Thu, Aug 19, 2010 at 2:02 PM, Ralph Castain <rhc_at_[hidden]> wrote:
>> > Something doesn't look right - here is what the algo attempts to do:
>> > given a port range of 10000-12000, the lowest rank'd process on the node
>> > should open port 10000. The next lowest rank on the node will open
>> > 10001,
>> > etc.
>> > So it looks to me like there is some confusion in the local rank algo.
>> > I'll
>> > have to look at the generic module - must be a bug in it somewhere.
>> > This might take a couple of days as I have surgery tomorrow morning, so
>> > please forgive the delay.
>> >
>> > On Thu, Aug 19, 2010 at 11:13 AM, Philippe <philmpi_at_[hidden]>
>> > wrote:
>> >>
>> >> Ralph,
>> >>
>> >> I'm able to use the generic module when the processes are on different
>> >> machines.
>> >>
>> >> what would be the values of the EV when two processes are on the same
>> >> machine (hopefully talking over SHM).
>> >>
>> >> i've played with combination of nodelist and ppn but no luck. I get
>> >> errors
>> >> like:
>> >>
>> >>
>> >>
>> >> [c0301b10e1:03172] [[0,9999],1] -> [[0,0],0] (node: c0301b10e1)
>> >> oob-tcp: Number of attempts to create TCP connection has been
>> >> exceeded.  Can not communicate with peer
>> >> [c0301b10e1:03172] [[0,9999],1] ORTE_ERROR_LOG: Unreachable in file
>> >> grpcomm_hier_module.c at line 303
>> >> [c0301b10e1:03172] [[0,9999],1] ORTE_ERROR_LOG: Unreachable in file
>> >> base/grpcomm_base_modex.c at line 470
>> >> [c0301b10e1:03172] [[0,9999],1] ORTE_ERROR_LOG: Unreachable in file
>> >> grpcomm_hier_module.c at line 484
>> >>
>> >> --------------------------------------------------------------------------
>> >> It looks like MPI_INIT failed for some reason; your parallel process is
>> >> likely to abort.  There are many reasons that a parallel process can
>> >> fail during MPI_INIT; some of which are due to configuration or
>> >> environment
>> >> problems.  This failure appears to be an internal failure; here's some
>> >> additional information (which may only be relevant to an Open MPI
>> >> developer):
>> >>
>> >>  orte_grpcomm_modex failed
>> >>  --> Returned "Unreachable" (-12) instead of "Success" (0)
>> >>
>> >> --------------------------------------------------------------------------
>> >> *** The MPI_Init() function was called before MPI_INIT was invoked.
>> >> *** This is disallowed by the MPI standard.
>> >> *** Your MPI job will now abort.
>> >> [c0301b10e1:3172] Abort before MPI_INIT completed successfully; not
>> >> able to guarantee that all other processes were killed!
>> >>
>> >>
>> >> maybe a related question is how to assign the TCP port range and how
>> >> is it used? when the processes are on different machines, I use the
>> >> same range and that's ok as long as the range is free. but when the
>> >> processes are on the same node, what value should the range be for
>> >> each process? My range is 10000-12000 (for both processes) and I see
>> >> that process with rank #0 listen on port 10001 while process with rank
>> >> #1 try to establish a connect to port 10000.
>> >>
>> >> Thanks so much!
>> >> p. still here... still trying... ;-)
>> >>
>> >> On Tue, Jul 27, 2010 at 12:58 AM, Ralph Castain <rhc_at_[hidden]>
>> >> wrote:
>> >> > Use what hostname returns - don't worry about IP addresses as we'll
>> >> > discover them.
>> >> >
>> >> > On Jul 26, 2010, at 10:45 PM, Philippe wrote:
>> >> >
>> >> >> Thanks a lot!
>> >> >>
>> >> >> now, for the ev "OMPI_MCA_orte_nodes", what do I put exactly? our
>> >> >> nodes have a short/long name (it's rhel 5.x, so the command hostname
>> >> >> returns the long name) and at least 2 IP addresses.
>> >> >>
>> >> >> p.
>> >> >>
>> >> >> On Tue, Jul 27, 2010 at 12:06 AM, Ralph Castain <rhc_at_[hidden]>
>> >> >> wrote:
>> >> >>> Okay, fixed in r23499. Thanks again...
>> >> >>>
>> >> >>>
>> >> >>> On Jul 26, 2010, at 9:47 PM, Ralph Castain wrote:
>> >> >>>
>> >> >>>> Doh - yes it should! I'll fix it right now.
>> >> >>>>
>> >> >>>> Thanks!
>> >> >>>>
>> >> >>>> On Jul 26, 2010, at 9:28 PM, Philippe wrote:
>> >> >>>>
>> >> >>>>> Ralph,
>> >> >>>>>
>> >> >>>>> i was able to test the generic module and it seems to be working.
>> >> >>>>>
>> >> >>>>> one question tho, the function orte_ess_generic_component_query
>> >> >>>>> in
>> >> >>>>> "orte/mca/ess/generic/ess_generic_component.c" calls getenv with
>> >> >>>>> the
>> >> >>>>> argument "OMPI_MCA_enc", which seems to cause the module to fail
>> >> >>>>> to
>> >> >>>>> load. shouldnt it be "OMPI_MCA_ess" ?
>> >> >>>>>
>> >> >>>>> .....
>> >> >>>>>
>> >> >>>>>   /* only pick us if directed to do so */
>> >> >>>>>   if (NULL != (pick = getenv("OMPI_MCA_env")) &&
>> >> >>>>>                0 == strcmp(pick, "generic")) {
>> >> >>>>>       *priority = 1000;
>> >> >>>>>       *module = (mca_base_module_t *)&orte_ess_generic_module;
>> >> >>>>>
>> >> >>>>> ...
>> >> >>>>>
>> >> >>>>> p.
>> >> >>>>>
>> >> >>>>> On Thu, Jul 22, 2010 at 5:53 PM, Ralph Castain <rhc_at_[hidden]>
>> >> >>>>> wrote:
>> >> >>>>>> Dev trunk looks okay right now - I think you'll be fine using
>> >> >>>>>> it.
>> >> >>>>>> My new component -might- work with 1.5, but probably not with
>> >> >>>>>> 1.4. I haven't
>> >> >>>>>> checked either of them.
>> >> >>>>>>
>> >> >>>>>> Anything at r23478 or above will have the new module. Let me
>> >> >>>>>> know
>> >> >>>>>> how it works for you. I haven't tested it myself, but am pretty
>> >> >>>>>> sure it
>> >> >>>>>> should work.
>> >> >>>>>>
>> >> >>>>>>
>> >> >>>>>> On Jul 22, 2010, at 3:22 PM, Philippe wrote:
>> >> >>>>>>
>> >> >>>>>>> Ralph,
>> >> >>>>>>>
>> >> >>>>>>> Thank you so much!!
>> >> >>>>>>>
>> >> >>>>>>> I'll give it a try and let you know.
>> >> >>>>>>>
>> >> >>>>>>> I know it's a tough question, but how stable is the dev trunk?
>> >> >>>>>>> Can
>> >> >>>>>>> I
>> >> >>>>>>> just grab the latest and run, or am I better off taking your
>> >> >>>>>>> changes
>> >> >>>>>>> and copy them back in a stable release? (if so, which one? 1.4?
>> >> >>>>>>> 1.5?)
>> >> >>>>>>>
>> >> >>>>>>> p.
>> >> >>>>>>>
>> >> >>>>>>> On Thu, Jul 22, 2010 at 3:50 PM, Ralph Castain
>> >> >>>>>>> <rhc_at_[hidden]>
>> >> >>>>>>> wrote:
>> >> >>>>>>>> It was easier for me to just construct this module than to
>> >> >>>>>>>> explain how to do so :-)
>> >> >>>>>>>>
>> >> >>>>>>>> I will commit it this evening (couple of hours from now) as
>> >> >>>>>>>> that
>> >> >>>>>>>> is our standard practice. You'll need to use the developer's
>> >> >>>>>>>> trunk, though,
>> >> >>>>>>>> to use it.
>> >> >>>>>>>>
>> >> >>>>>>>> Here are the envars you'll need to provide:
>> >> >>>>>>>>
>> >> >>>>>>>> Each process needs to get the same following values:
>> >> >>>>>>>>
>> >> >>>>>>>> * OMPI_MCA_ess=generic
>> >> >>>>>>>> * OMPI_MCA_orte_num_procs=<number of MPI procs>
>> >> >>>>>>>> * OMPI_MCA_orte_nodes=<a comma-separated list of nodenames
>> >> >>>>>>>> where
>> >> >>>>>>>> MPI procs reside>
>> >> >>>>>>>> * OMPI_MCA_orte_ppn=<number of procs/node>
>> >> >>>>>>>>
>> >> >>>>>>>> Note that I have assumed this last value is a constant for
>> >> >>>>>>>> simplicity. If that isn't the case, let me know - you could
>> >> >>>>>>>> instead provide
>> >> >>>>>>>> it as a comma-separated list of values with an entry for each
>> >> >>>>>>>> node.
>> >> >>>>>>>>
>> >> >>>>>>>> In addition, you need to provide the following value that will
>> >> >>>>>>>> be
>> >> >>>>>>>> unique to each process:
>> >> >>>>>>>>
>> >> >>>>>>>> * OMPI_MCA_orte_rank=<MPI rank>
>> >> >>>>>>>>
>> >> >>>>>>>> Finally, you have to provide a range of static TCP ports for
>> >> >>>>>>>> use
>> >> >>>>>>>> by the processes. Pick any range that you know will be
>> >> >>>>>>>> available across all
>> >> >>>>>>>> the nodes. You then need to ensure that each process sees the
>> >> >>>>>>>> following
>> >> >>>>>>>> envar:
>> >> >>>>>>>>
>> >> >>>>>>>> * OMPI_MCA_oob_tcp_static_ports=6000-6010  <== obviously,
>> >> >>>>>>>> replace
>> >> >>>>>>>> this with your range
>> >> >>>>>>>>
>> >> >>>>>>>> You will need a port range that is at least equal to the ppn
>> >> >>>>>>>> for
>> >> >>>>>>>> the job (each proc on a node will take one of the provided
>> >> >>>>>>>> ports).
>> >> >>>>>>>>
>> >> >>>>>>>> That should do it. I compute everything else I need from those
>> >> >>>>>>>> values.
>> >> >>>>>>>>
>> >> >>>>>>>> Does that work for you?
>> >> >>>>>>>> Ralph
>> >> >>>>>>>>
>> >> >>>>>>>>
>> >> >>
>> >> >> _______________________________________________
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>> >> >> users_at_[hidden]
>> >> >> http://www.open-mpi.org/mailman/listinfo.cgi/users
>> >> >
>> >> >
>> >> > _______________________________________________
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>> >>
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