NAME

       mpitask - Monitor MPI processes under LAM.

SYNOPSIS

       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

       TASK (G/L)    FUNCTION   PEER|ROOT   TAG   COMM    COUNT   DATATYPE
       0/0 trivial   Ssend      1/1         123   WORLD   64      INT
       1/1 trivial   Recv       0/0         456   WORLD   64      INT

       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 nnode,iindex.  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)