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)