NAME
MPI_Testall - Tests for the completion of all previously initiated
communications
SYNOPSIS
#include <mpi.h>
int MPI_Testall(int count, MPI_Request *reqs,
int *flag, MPI_Status *stats)
INPUT PARAMETERS
count - lists length (integer)
reqs - array of requests (array of handles)
OUTPUT PARAMETERS
flag - (logical)
stats - array of status objects (array of Status), which can be the
MPI constant MPI_STATUSES_IGNORE
NOTES
flag is true (1) only if all requests have completed. Otherwise, flag
is false (0) and neither reqs nor stats is modified.
NOTE ON STATUS FOR SEND OPERATIONS
For send operations, the only use of status is for MPI_Test_cancelled
in the case that there is an error, in which case the MPI_ERROR field
of status will be set.
NOTES FOR FORTRAN
All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK ) have
an additional argument ierr at the end of the argument list. ierr is
an integer and has the same meaning as the return value of the routine
in C. In Fortran, MPI routines are subroutines, and are invoked with
the call statement.
All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in
Fortran.
ERRORS
If an error occurs in an MPI function, the current MPI error handler is
called to handle it. By default, this error handler aborts the MPI
job. The error handler may be changed with MPI_Errhandler_set ; the
predefined error handler MPI_ERRORS_RETURN may be used to cause error
values to be returned (in C and Fortran; this error handler is less
useful in with the C++ MPI bindings. The predefined error handler
MPI::ERRORS_THROW_EXCEPTIONS should be used in C++ if the error value
needs to be recovered). Note that MPI does not guarantee that an MPI
program can continue past an error.
All MPI routines (except MPI_Wtime and MPI_Wtick ) return an error
value; C routines as the value of the function and Fortran routines in
the last argument. The C++ bindings for MPI do not return error
values; instead, error values are communicated by throwing exceptions
of type MPI::Exception (but not by default). Exceptions are only
thrown if the error value is not MPI::SUCCESS .
Note that if the MPI::ERRORS_RETURN handler is set in C++, while MPI
functions will return upon an error, there will be no way to recover
what the actual error value was.
MPI_SUCCESS
- No error; MPI routine completed successfully.
MPI_ERR_COUNT
- Invalid count argument. Count arguments must be non-negative;
a count of zero is often valid.
MPI_ERR_ARG
- Invalid argument. Some argument is invalid and is not
identified by a specific error class. This is typically a NULL
pointer or other such error.
MPI_ERR_IN_STATUS
- The actual error value is in the MPI_Status argument. Note
that if this error occurs and MPI_STATUS_IGNORE or
MPI_STATUSES_IGNORE was used as the status argument, the actual
error will be lost. This error class is returned only from the
multiple-completion routines ( MPI_Testall , MPI_Testany ,
MPI_Testsome , MPI_Waitall , MPI_Waitany , and MPI_Waitsome ).
The field MPI_ERROR in the status argument contains the error
value or MPI_SUCCESS (no error and complete) or MPI_ERR_PENDING
to indicate that the request has not completed. The MPI
Standard does not specify what the result of the multiple
completion routines is when an error occurs. For example, in an
MPI_WAITALL , does the routine wait for all requests to either
fail or complete, or does it return immediately (with the MPI
definition of immediately, which means independent of actions of
other MPI processes)? LAM/MPI has chosen to make the return
immediate (alternately, local in MPI terms), and to use the
error class MPI_ERR_PENDING (introduced in MPI 1.1) to indicate
which requests have not completed. In most cases, only one
request with an error will be detected in each call to an MPI
routine that tests multiple requests. The requests that have
not been processed (because an error occured in one of the
requests) will have their MPI_ERROR field marked with
MPI_ERR_PENDING .
MORE INFORMATION
For more information, please see the official MPI Forum web site, which
contains the text of both the MPI-1 and MPI-2 standards. These
documents contain detailed information about each MPI function (most of
which is not duplicated in these man pages).
http://www.mpi-forum.org/
ACKNOWLEDGEMENTS
The LAM Team would like the thank the MPICH Team for the handy program
to generate man pages ("doctext" from
ftp://ftp.mcs.anl.gov/pub/sowing/sowing.tar.gz ), the initial
formatting, and some initial text for most of the MPI-1 man pages.
LOCATION
testall.c