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<DIV dir=ltr align=left><SPAN class=204005109-04092008><FONT face=Arial
color=#0000ff size=2>Good point. At face value, this seems to suggest that we
should have "extended" constructors available on a level with the traditional
ones, thus favoring the original name-shifted proposal. If I think about the
library internals in this case, however, this addition will effectively push all
of the library extent calculations to 64-bit (or more, see
below).</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=204005109-04092008><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=204005109-04092008><FONT face=Arial
color=#0000ff size=2>Another thing is that if we multiply to long values, the
result may potentially overflow a long. So, for a library that allows long
counts and long datatype extents, the internals of the library will have to be
long long. long long (128 bit) arithmetic may be rather expensive on some CPUs.
So, the 64-bit interface should probably be optional.</FONT></SPAN></DIV><BR>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>From:</B> mpi-22-bounces@lists.mpi-forum.org
[mailto:mpi-22-bounces@lists.mpi-forum.org] <B>On Behalf Of </B>Richard
Treumann<BR><B>Sent:</B> Wednesday, September 03, 2008 7:24 PM<BR><B>To:</B> MPI
2.2<BR><B>Subject:</B> Re: [Mpi-22] New proposal: Support for large message
counts<BR></FONT><BR></DIV>
<DIV></DIV>
<P>MPI_Aint has the right number of bits to hold an address. For operations that
are address space oriented, count can be the same size as an
MPI_Aint<BR><BR>MPI_Offset has the right number of bits to deal with the range
in a file. For operations that are file oriented, arguments like count should be
an MPI_Offset<BR><BR>A problem is that MPI_Datatype constructors are intended to
apply to both and it is common for a 32 bit address space to operate on files
with 64 bit offsets. <BR><BR>What type should "count" on the new "long"
MPI_Datatype constructors be in this case? The proposal says MPI_Aint but that
is awkward for datatypes as fileviews.<BR><BR><BR>Dick Treumann - MPI Team
<BR>IBM Systems & Technology Group<BR>Dept X2ZA / MS P963 -- 2455 South Road
-- Poughkeepsie, NY 12601<BR>Tele (845) 433-7846 Fax (845)
433-8363<BR><BR><BR><TT>mpi-22-bounces@lists.mpi-forum.org wrote on 09/03/2008
12:38:35 PM:<BR><BR>> [image removed] </TT><BR><TT>> <BR>> Re: [Mpi-22]
New proposal: Support for large message counts</TT><BR><TT>> <BR>>
Supalov, Alexander </TT><BR><TT>> <BR>> to:</TT><BR><TT>> <BR>> MPI
2.2</TT><BR><TT>> <BR>> 09/03/2008 12:48 PM</TT><BR><TT>> <BR>> Sent
by:</TT><BR><TT>> <BR>>
mpi-22-bounces@lists.mpi-forum.org</TT><BR><TT>> <BR>> Please respond to
"MPI 2.2"</TT><BR><TT>> <BR>> Thanks. We may even do without changing the
MPI routine names I think.<BR>> Let's consider this:<BR>> <BR>> 1)
#define MPI_Count int will yield the current MPI interface.<BR>> 2) typedef
int MPI_Count will yield the new 32-bit interface, still<BR>> backward binary
compatible with 1).<BR>> 3) typedef long MPI_Count will yield new 64-bit
interface.<BR>> 4) typedef long long MPI_Count will safely bring us into XXII
century<BR>> (or earlier).<BR>> <BR>> Old applications may be rebuilt
using 1) without any changes,<BR>> dynamically linked against MPI library
built using 2), and will have to<BR>> be rebuilt to use MPI library built
using 3) or 4).<BR>> <BR>> New applications will use library with the
MPI_Count definitions, and,<BR>> properly rebuilt, will work in either 32-,
64-, or 128-bit mode, using<BR>> MPI libraries built using MPI bindings 2),
3), or 4), respectively.<BR>> <BR>> By the way, should MPI_Count really be
signed?<BR>> <BR>> -----Original Message-----<BR>> From:
mpi-22-bounces@lists.mpi-forum.org<BR>> [<A
href="mailto:mpi-22-bounces@lists.mpi-forum.org">mailto:mpi-22-bounces@lists.mpi-forum.org</A>]
On Behalf Of Narasimhan,<BR>> Kannan<BR>> Sent: Wednesday, September 03,
2008 5:55 PM<BR>> To: MPI 2.2<BR>> Subject: Re: [Mpi-22] New proposal:
Support for large message counts<BR>> <BR>> We can certainly consider this
option, since it abstracts along the same<BR>> lines as MPI_Offset.<BR>>
<BR>> Thanx!<BR>> Kannan<BR>> <BR>> -----Original
Message-----<BR>> From: mpi-22-bounces@lists.mpi-forum.org<BR>> [<A
href="mailto:mpi-22-bounces@lists.mpi-forum.org">mailto:mpi-22-bounces@lists.mpi-forum.org</A>]
On Behalf Of Supalov,<BR>> Alexander<BR>> Sent: Wednesday, September 03,
2008 10:19 AM<BR>> To: MPI 2.2<BR>> Subject: Re: [Mpi-22] New proposal:
Support for large message counts<BR>> <BR>> Dear Kannan,<BR>> <BR>>
Thanks. Why don't we define MPI_Count datatype instead, and make that<BR>>
grow if necessary?<BR>> <BR>> Best regards.<BR>> <BR>>
Alexander<BR>> <BR>> -----Original Message-----<BR>> From:
mpi-22-bounces@lists.mpi-forum.org<BR>> [<A
href="mailto:mpi-22-bounces@lists.mpi-forum.org">mailto:mpi-22-bounces@lists.mpi-forum.org</A>]
On Behalf Of Narasimhan,<BR>> Kannan<BR>> Sent: Friday, August 29, 2008
6:15 PM<BR>> To: mpi-22@lists.mpi-forum.org<BR>> Subject: [Mpi-22] New
proposal: Support for large message counts<BR>> <BR>> I have submitted a
new 2.2 proposal to addresses the need for large<BR>> message counts (i.e.
counts greater than the size of 32-bit integer) for<BR>> MPI calls that
communicate messages.<BR>> <BR>> Please refer to<BR>> <A
href="https://svn.mpi-forum.org/trac/mpi-forum-web/wiki/mpi22/LargeMsgCounts">https://svn.mpi-forum.org/trac/mpi-forum-web/wiki/mpi22/LargeMsgCounts</A><BR>>
for details.<BR>> <BR>> Comments and suggestions are welcome.<BR>>
<BR>> Thanx!<BR>> Kannan<BR>> <BR>>
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