mpitask - Monitor MPI processes under LAM.
SYNTAX
mpitask [-cdh] [-gps] [<nodes>] [<processes>]
OPTIONS
-c Print communicator descriptions. See "Communica
tors".
-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 report
ed 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 in
formation:
TASK an identification of the process - If the pro
cess is currently communicating, a `/' followed
by the process's rank within the current commu
nicator is also displayed. The executable name,
if available, is also displayed. See "MPI Pro
cess Identification".
FUNCTION an abbreviated form of the function name if the
process is blocked inside an MPI function - Oth
erwise 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_SIGAR
REST - See doom(1).
<blocked> blocked in a LAM function - In general
this should be a transitory state.
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 communica
tor -
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 dis
played with a * suffix. Further information on
the communicator may be obtained with the -c op
tion.
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 speci
fied 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. Fur
ther 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 em
ployed communicator is referred to as the "local" rank
(L).
Since processes may be dynamically spawned (see
MPIL_Spawn(2)) and since multiple concurrent MPI applica
tions are allowed, it is possible for multiple
MPI_COMM_WORLD communicators to coexist. In these situa
tions, 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 (Glob
al Positioning System). A process's GPS consists of the
nodeid the process is running on and the process's LAM in
dex 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. In
stead for each selected process currently using a communi
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. In
stead for each selected process currently using a communi
cator, 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 dis
played.
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)
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