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NAME

       mpitask - Monitor MPI processes under LAM.

SYNTAX

       mpitask [-cdh] [-gps] [<nodes>] [<processes>]

OPTIONS

       -c      Print communicator descriptions.  See "Communicators".

       -d      Print datatype descriptions.  See "Datatypes".

       -gps    Print process information in GPS format.

       -h      Print useful information on this command.

       The -c and -d options are mutually exclusive.

DESCRIPTION

       The  mpitask  command  displays information on processes which are using MPI.  One line is
       printed for each reported MPI process.  With no processes or nodes explicitly specified on
       the command line, all MPI processes on all nodes are reported.

% mpitask
       For each process mpitask normally prints the following information:

       TASK      an  identification of the process - If the process is currently communicating, a
                 `/' followed by the process's rank  within  the  current  communicator  is  also
                 displayed.   The  executable  name,  if  available, is also displayed.  See "MPI
                 Process Identification".

       FUNCTION  an abbreviated form of the function name if the process is blocked inside an MPI
                 function - Otherwise one of the following execution states is printed:

                 <running> free to run on the underlying OS

                 <paused>  blocked on lam_kpause(2)

                 <stopped> stopped by the LAM signal, LAM_SIGARREST - See doom(1).

                 <blocked> blocked  in  a  LAM  function - In general this should be a transitory
                           state.  Further information on a LAM process's state can  be  obtained
                           with state(1).

       PEER|ROOT the  source or destination of a point-to-point communication or the root process
                 of certain collective communications, followed by a '/' and the  process's  rank
                 within the current communicator -

       TAG       the  message  tag, if any, which was specified as a parameter to the current MPI
                 function

       COMM      the communicator ID, if any, which was specified as a parameter to  the  current
                 MPI  function  -  Communicators  used in collective calls are displayed with a *
                 suffix.  Further information on the communicator may be  obtained  with  the  -c
                 option.

       COUNT     the element count, if any, which was specified as a parameter to the current MPI
                 function

       DATATYPE  the element datatype, if any, which was specified as a parameter to the  current
                 MPI function - For intrinsic datatypes, a shortened version of the datatype name
                 is displayed.  For derived datatypes, a datatype label  is  displayed.   Further
                 information on the datatype may be obtained with the -d option.

   MPI Process Identification
       By  default,  MPI  processes  are identified by their rank in MPI_COMM_WORLD.  We refer to
       this rank more concisely as the "global" rank (G).  The rank within the currently employed
       communicator is referred to as the "local" rank (L).

       Since  processes  may  be  dynamically  spawned  (see  MPIL_Spawn(2))  and  since multiple
       concurrent MPI applications are  allowed,  it  is  possible  for  multiple  MPI_COMM_WORLD
       communicators  to  coexist.   In  these  situations, the global rank is no longer globally
       unique and the identification is ambiguous.   Thus,  LAM  provides  an  alternate  way  of
       identifying  MPI processes, the GPS (Global Positioning System).  A process's GPS consists
       of the nodeid the process is running on and the process's LAM index on that node.   It  is
       displayed  in  mpitask as the pair n<node>,i<index>.  If the -gps option is given then the
       GPS is substituted for the global rank (G).

   Communicators
       If the -c option is given then information is no longer displayed in the horizontal format
       described  above.   Instead  for each selected process currently using a communicator, the
       information from the TASK column, described  above,  is  given  followed  by  an  expanded
       description  of  the communicator.  This description includes the size of the communicator
       group(s) and the global identifiers of all members of the group(s).

   Datatypes
       If the -d option is given then information is no longer displayed in the horizontal format
       described  above.   Instead  for each selected process currently using a communicator, the
       information from the TASK column, described above, is given  followed  by  the  datatype's
       type map.

EXAMPLES

       mpitask
           Display the status of all MPI processes on all nodes.

       mpitask -c n0 i9
           Display the communicator (if any) of process index 9 on node 0.

DIAGNOSTICS

       If no MPI processes are found, only the title line is displayed.

BUGS

       Sometimes  processes  may  be  shown  as blocked inside a non-blocking MPI function.  This
       occurs when the process is blocked inside the MPI function on  some  internal  LAM  event.
       Such states are highly transitory.

SEE ALSO

       doom(1), libmpi(3), mpirun(1), mpimsg(1), state(1), MPIL_Comm_id(2), MPIL_Type_id(2)