91 строка
4.1 KiB
Groff
91 строка
4.1 KiB
Groff
.\"Copyright 2006, Sun Microsystems, Inc. All rights reserved. Use is subject to license terms.
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.\" Copyright (c) 1996 Thinking Machines Corporation
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.TH MPI_Testsome 3OpenMPI "September 2006" "Open MPI 1.2" " "
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.SH NAME
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\fBMPI_Testsome\fP \- Tests for completion of one or more previously initiated communications in a list.
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.SH SYNTAX
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.ft R
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.SH C Syntax
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.nf
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#include <mpi.h>
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int MPI_Testsome(int \fIincount\fP, MPI_Request \fI*array_of_requests\fP,
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int\fI *outcount\fP, int\fI *array_of_indices\fP, MPI_Status\fI *array_of_statuses\fP)
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.SH Fortran Syntax
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.nf
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INCLUDE 'mpif.h'
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MPI_TESTSOME(\fIINCOUNT, ARRAY_OF_REQUESTS, OUTCOUNT,
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ARRAY_OF_INDICES, ARRAY_OF_STATUSES, IERROR\fP)
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INTEGER \fIINCOUNT, ARRAY_OF_REQUESTS(*)\fP
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INTEGER \fIOUTCOUNT, ARRAY_OF_INDICES(*)\fP
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INTEGER \fIARRAY_OF_STATUSES(MPI_STATUS_SIZE,*), IERROR\fP
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.SH C++ Syntax
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.nf
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#include <mpi.h>
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static int Request::Testsome(int \fIincount\fP, Request
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\fIarray_of_requests\fP[], int \fIarray_of_indices\fP[], Status \fIarray_of_statuses\fP[])
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static int Request::Testsome(int \fIincount\fP, Request
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\fIarray_of_requests\fP[], int \fIarray_of_indices\fP[])
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.SH INPUT PARAMETERS
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.ft R
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.TP 1i
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incount
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Length of array_of_requests (integer).
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.TP 1i
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array_of_requests
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Array of requests (array of handles).
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.SH OUTPUT PARAMETERS
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.ft R
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.TP 1i
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outcount
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Number of completed requests (integer).
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.TP 1i
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array_of_indices
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Array of indices of operations that completed (array of integers).
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.TP 1i
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array_of_statuses
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Array of status objects for operations that completed (array of status).
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.ft R
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.TP 1i
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IERROR
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Fortran only: Error status (integer).
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.SH DESCRIPTION
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.ft R
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Behaves like MPI_Waitsome, except that it returns immediately. If no operation has completed it returns outcount = 0. If there is no active handle in the list, it returns outcount = MPI_UNDEFINED.
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.sp
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MPI_Testsome is a local operation, which returns immediately, whereas MPI_Waitsome blocks until a communication completes, if it was passed a list that contains at least one active handle. Both calls fulfill a fairness requirement: If a request for a receive repeatedly appears in a list of requests passed to MPI_Waitsome or MPI_Testsome, and a matching send has been posted, then the receive will eventually succeed unless the send is satisfied by another receive; send requests also fulfill this fairness requirement.
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.sp
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Errors that occur during the execution of MPI_Testsome are handled as for
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MPI_Waitsome.
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.sp
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If your application does not need to examine the \fIarray_of_statuses\fP field, you can save resources by using the predefined constant MPI_STATUSES_IGNORE can be used as a special value for the \fIarray_of_statuses\fP argument.
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.SH NOTES
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The use of MPI_Testsome is likely to be more
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efficient than the use of MPI_Testany. The former returns information on all completed communications; with the latter, a new call is required for each communication that completes.
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.sp
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A server with multiple clients can use MPI_Waitsome so as not to starve any client. Clients send messages to the server with service requests. The server calls MPI_Waitsome with one receive request for each client, then handles all receives that have completed. If a call to MPI_Waitany is used instead, then one client could starve while requests from another client always sneak in first.
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.SH ERRORS
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Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument. C++ functions do not return errors. If the default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism will be used to throw an MPI:Exception object.
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.sp
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Before the error value is returned, the current MPI error handler is
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called. By default, this error handler aborts the MPI job, except for I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.
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.SH SEE ALSO
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.ftR
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.sp
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MPI_Waitsome
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.br
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MPI_Waitany
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.br
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MPI_Testany
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' @(#)MPI_Testsome.3 1.20 06/03/09
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