# [Mpi-forum] Feedback needed / Suggested Change to Chapter 8 (related to RMA)

Schulz, Martin schulzm at llnl.gov
Thu Jul 19 11:05:56 CDT 2012

Hi all,

during the final chapter reads, the following issue came up in the section "Memory Allocation" in Chapter 8, MPI Environmental Management. Here is the context

> \section{Memory Allocation}
> \label{sec:misc-memalloc}
>
> In some systems, message-passing and remote-memory-access (\RMA/) operations
> run faster when accessing specially allocated memory (e.g., memory that is
> shared by the other processes in the communicating group on an SMP).  \MPI/
> provides a mechanism for allocating and freeing such special memory.  The use
> of such memory for message-passing or \RMA/ is not mandatory, and this memory
> can be used without restrictions as any other dynamically allocated memory.

This is followed by the following sentence:

> However, implementations may restrict the use of the \mpifunc{MPI\_WIN\_LOCK}
> and \mpifunc{MPI\_WIN\_UNLOCK} functions to windows allocated in such memory
> (see Section~\ref{sec:1sided-lock}.)

This covers the restrictions for 2.2, but not for the new RMA chapter. Therefore, the RMA group (or a subset thereof) suggested to change that sentence to:

> However, implementations may restrict the use of some RMA functionality as defined
> in Section~\ref{sec:1sided-lock}.

and leave the definition of the semantics to the RMA chapter.

Please reply to the group if there are any objections or concerns.

Thanks,

Martin

________________________________________________________________________
Martin Schulz, schulzm at llnl.gov, http://people.llnl.gov/schulzm
CASC @ Lawrence Livermore National Laboratory, Livermore, USA