attroverview.tex

刚才是说明 现在是安装程序在 LINUX环境下进行编程的MPICH安装文件

 The MPI standard allows \emph{attributes}, essentially an \texttt{(integer,pointer)}
 pair, to be attached to communicators, windows, and datatypes.  
 The integer is a \emph{keyval}, which is allocated by a call (at the MPI level)
 to \texttt{MPI_Comm/Type/Win_create_keyval}.  The pointer is the value of 
 the attribute.
 Attributes are primarily intended for use by the user, for example, to save
 information on a communicator, but can also be used to pass data to the
 MPI implementation.  For example, an attribute may be used to pass 
 Quality of Service information to an implementation to be used with 
 communication on a particular communicator.  
 To provide the most general access by the ADI to all attributes, the
 ADI defines a collection of routines that are used by the implementation
 of the MPI attribute routines (such as \texttt{MPI_Comm_get_attr}).
 In addition, the MPI routines involving attributes will invoke the 
 corresponding \texttt{hook} functions (e.g., \texttt{MPID_Dev_comm_attr_set_hook}) 
 should the device define them.

 Attributes on windows and datatypes are defined by MPI but not of interest (as yet) 
 to the device.

 In addition, there are seven predefined attributes that the device must
 supply to the implementation.  This is accomplished through 
 data values that are part of the \texttt{MPIR_Process} data block.
  The predefined keyvals on \texttt{MPI_COMM_WORLD} are:
\begin{verbatim}
 Keyval                     Related Module
 MPI_APPNUM                 Dynamic
 MPI_HOST                   Core
 MPI_IO                     Core
 MPI_LASTUSEDCODE           Error
 MPI_TAG_UB                 Communication
 MPI_UNIVERSE_SIZE          Dynamic
 MPI_WTIME_IS_GLOBAL        Timer
\end{verbatim}
 The values stored in the \texttt{MPIR_Process} block are the actual values.  For 
 example, the value of \texttt{MPI_TAG_UB} is the integer value of the largest tag.
 The
 value of \texttt{MPI_WTIME_IS_GLOBAL} is a \texttt{1} for true and \texttt{0} for false.  Likely
 values for \texttt{MPI_IO} and \texttt{MPI_HOST} are \texttt{MPI_ANY_SOURCE} and \texttt{MPI_PROC_NULL}
 respectively.