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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)