mpitask - Online in the Cloud

PROGRAM:

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.

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