mpimsg - Monitor MPI message buffers under LAM.

       The  mpimsg  command  displays information on buffered messages which were sent using the MPI library and
       are currently buffered on the specified nodes and destined to the specified processes.  mpimsg  typically
       only  works  when  the  "daemon"  mode  of communication is used; it cannot be used to monitor "client to
       client" (C2C) communications.

       With no processes or nodes explicitly specified on the command line, all MPI messages on  all  nodes  are
       reported.

       % mpimsg
       SRC (G/L)   DEST (G/L)   TAG   COMM    COUNT   DATATYPE   MSG
       0/0         1/1          123   WORLD   64      INT        n1,#0

       For each message mpimsg outputs the following information:

       SRC            an  identification of the source process - A `/' followed by the process's rank within the
                      message's communicator is also displayed.  See mpitask(1)  for  a  discussion  of  process
                      identification.

       DEST           an identification of the destination process

       TAG            the tag from the message envelope

       COMM           the communicator identifier

       COUNT          the number of data elements in the message

       DATATYPE       the element datatype

       MSG            the  message identifier - It is expressed in the form nnodeid,#seqnum, where nodeid is the
                      physical location of the buffered message and seqnum is a sequence number assigned to  the
                      message  by  LAM.   These  values are used to get further information on the communicator,
                      datatype or message contents.

       More detailed information on the message's communicator or datatype can be obtained with the -c or -d op‐
       tions.  The information is the same as obtained by mpitask(1) regarding  processes.   Unlike  mpitask(1),
       these  options  in  mpimsg  require  a message identifier to isolate a single message.  Keep in mind that
       mpimsg invocations are snapshots of system status.  It is possible that a buffered  message  shown  in  a
       call  of mpimsg may be received prior to a subsequent call to mpimsg made in order to display further in‐
       formation.  In this case nothing is printed.

   MessageContents
       If the -m option is given then the contents of the specified message are displayed.

       First the destination process identification and the message identification is printed and then the  mes‐
       sage  contents  are  printed in a format somewhat similar to that produced by the UNIX utility od(1).  On
       the left hand side of each line the offset from the beginning of the data buffer is printed in  hexadeci‐
       mal.   After that individual elements are printed according to their type as deduced from the type signa‐
       ture.  Holes in the datatype and changes in basic type force newlines in the output so in effect all ele‐
       ments on the same line of output are actually contiguous in the buffer and of the same basic type.

       The amount of a message that is to be printed can be limited with the -e option.  The limit is  specified
       in  terms  of  a maximum number of elements of a basic datatype that are to be printed.  For example if a
       message consists of 100 structures with each structure containing three integers,  then  a  limit  of  20
       would  result  in  the display of the first 20 integers in the message, as opposed to the first 20 struc‐
       tures (or 60 integers).

       Buffered message data is by default stored in LAM representation and will be converted to local represen‐
       tation for display.  In the case of a homogeneous LAM and  MPI  processes  run  with  the  -O  switch  to
       mpirun(1)  message data will be stored in the common local representation of the machines in the LAM.  In
       this case when using the -m option the -O switch can be given in order to prevent the data conversion for
       display.

       If no buffered messages are found, only the title line is displayed.  If the message specified by -c,  -d
       or -m is no longer buffered, nothing is printed.

       mpimsg
           Report all MPI messages.

       mpimsg n1 -m 8 -e 20
           Print the first 20 elements of message #8 on node 1.

       mpimsg - Monitor MPI message buffers under LAM.

-gps           Print process information in GPS format.

       -h             Print useful information on this command.

       -O             Multicomputer is homogeneous.  Do no data conversion.  See mpirun(1).

       -cseq         Print a description of the communicator used in message seq.  See mpitask(1).

       -dseq         Print a description of the datatype used in message seq.  See mpitask(1).

       -enn          Limit printing the contents of a message to # elements.

       -mseq         Print the contents of message seq.  See "Message Contents".

       -Bnn          Change the limit on the number of messages reported.

       The -c, -d and -m options are mutually exclusive.

bfctl(1), bfstate(1), libmpi(3), mpitask(1), sweep(1)

LAM 7.1.4                                          July, 2007                                          MPIMSG(1)

       mpimsg [-gps] [-h] [-O] [-c seq] [-d seq] [-m seq] [-e #] [-B #] [nodes] [processes]