1 | .\"Copyright 2006-2008 Sun Microsystems, Inc. |
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2 | .\" Copyright (c) 1996 Thinking Machines Corporation |
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3 | .TH MPI_File_iread_at 3 "Dec 08, 2009" "1.4" "Open MPI" |
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4 | .SH NAME |
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5 | \fBMPI_File_iread_at\fP \- Reads a file at an explicitly specified offset (nonblocking, noncollective). |
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6 | |
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7 | .SH SYNTAX |
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8 | .ft R |
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9 | .nf |
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10 | C Syntax |
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11 | #include <mpi.h> |
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12 | int MPI_File_iread_at(MPI_File \fIfh\fP, MPI_Offset \fIoffset\fP, |
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13 | void \fI*buf\fP, int \fIcount\fP, MPI_Datatype \fIdatatype\fP, |
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14 | MPI_Request \fI*request\fP) |
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15 | |
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16 | Fortran Syntax (see FORTRAN 77 NOTES) |
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17 | INCLUDE 'mpif.h' |
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18 | MPI_FILE_IREAD_AT(\fIFH\fP, \fIOFFSET\fP, \fIBUF\fP, \fICOUNT\fP, \fIDATATYPE\fP, \fIREQUEST\fP, \fIIERROR\fP) |
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19 | <type> \fIBUF\fP(*) |
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20 | INTEGER \fIFH, COUNT, DATATYPE, REQUEST, IERROR\fP |
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21 | INTEGER(KIND=MPI_OFFSET_KIND) \fIOFFSET\fP |
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22 | |
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23 | .SH C++ Syntax |
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24 | .nf |
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25 | #include <mpi.h> |
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26 | MPI::Request MPI::File::Iread_at(MPI::Offset \fIoffset\fP, void* \fIbuf\fP, |
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27 | int \fIcount\fP, const MPI::Datatype& \fIdatatype\fP) |
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28 | |
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29 | .SH INPUT PARAMETERS |
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30 | .ft R |
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31 | .TP 1i |
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32 | fh |
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33 | File handle (handle). |
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34 | .ft R |
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35 | .TP 1i |
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36 | offset |
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37 | File offset (integer). |
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38 | .ft R |
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39 | .TP 1i |
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40 | count |
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41 | Number of elements in the buffer (integer). |
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42 | .ft R |
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43 | .TP 1i |
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44 | datatype |
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45 | Data type of each buffer element (handle). |
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46 | |
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47 | .SH OUTPUT PARAMETERS |
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48 | .ft R |
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49 | .TP 1i |
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50 | buf |
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51 | Initial address of the buffer (choice). |
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52 | .ft R |
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53 | .TP 1i |
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54 | request |
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55 | Request object (handle). |
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56 | .TP 1i |
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57 | IERROR |
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58 | Fortran only: Error status (integer). |
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59 | |
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60 | .SH DESCRIPTION |
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61 | .ft R |
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62 | MPI_File_iread_at is the nonblocking version of MPI_File_read_at. |
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63 | |
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64 | MPI_File_iread_at is a nonblocking routine that attempts to read from the file associated with |
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65 | .I fh |
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66 | at the |
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67 | .I offset |
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68 | position a total number of |
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69 | .I count |
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70 | data items having |
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71 | .I datatype |
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72 | type into the user's buffer |
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73 | .I buf. |
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74 | The |
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75 | .I offset |
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76 | is in etype units relative to the current view. That is, holes are not counted |
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77 | when locating an offset. The data is taken out of those parts of the |
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78 | file specified by the current view. MPI_File_iread_at stores the |
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79 | number of |
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80 | .I datatype |
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81 | elements actually read in |
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82 | .I status. |
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83 | All other fields of |
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84 | .I status |
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85 | are undefined. |
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86 | |
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87 | .SH FORTRAN 77 NOTES |
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88 | .ft R |
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89 | The MPI standard prescribes portable Fortran syntax for |
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90 | the \fIOFFSET\fP argument only for Fortran 90. Sun FORTRAN 77 |
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91 | users may use the non-portable syntax |
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92 | .sp |
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93 | .nf |
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94 | INTEGER*MPI_OFFSET_KIND \fIOFFSET\fP |
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95 | .fi |
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96 | .sp |
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97 | where MPI_OFFSET_KIND is a constant defined in mpif.h |
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98 | and gives the length of the declared integer in bytes. |
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99 | |
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100 | .SH ERRORS |
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101 | 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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102 | .sp |
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103 | Before the error value is returned, the current MPI error handler is |
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104 | called. For MPI I/O function errors, the default error handler is set to MPI_ERRORS_RETURN. The error handler may be changed with MPI_File_set_errhandler; the predefined error handler MPI_ERRORS_ARE_FATAL may be used to make I/O errors fatal. Note that MPI does not guarantee that an MPI program can continue past an error. |
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105 | |
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