Re: [pooma-dev] Re: [PATCH] Robustify async MPI request handling

[Jeffrey D. Oldham]

Richard Guenther wrote:

> On Mon, 16 Aug 2004, Jeffrey D. Oldham wrote:
>
>  
>
> > Richard Guenther wrote:
> >
> >    
> >
> > > The following patch fixes an error and robustifies MPI request handling.
> > >
> > > Tested by having it in my local tree for a long time.
> > >
> > > Ok?
> > >
> > > Richard.
> > >
> > >
> > > 2004Aug16  Richard Guenther <address@hidden>
> > >
> > >    * src/Threads/IterateSchedulers/SerialAsync.h: Guard against
> > >    LAM MPI automatically dragging in C++ support, fix message
> > >    polling return value check, complete messages first, remove
> > >    unused variable.
> > >      
> > What problems does mpicxx.h cause?  I am both curious and want to know
> > so I can approve the patch.
> >    
>
> The problem is incompatible C++ ABIs for the compiler used to build LAM
> (gcc 2.95) and the compiler I try to build POOMA with (gcc 3.4), so
> linking will fail either with ABI problems or missing symbols if not
> linking the C++ support libraries (as the header somehow manages to pull
> symbols regardless of not using any of the C++ support).  As we don't use
> any of the MPI C++ API we don't need its declarations either.  Other
> MPI implementations require you to explicitly pull mpicxx.h, but LAM aims
> to be clever in just doing
>
> #ifdef __cplusplus
> #include <mpicxx.h>
> #endif
>
> which I think is a bug in LAM, but can be easily worked around by us.
>
> But I can leave this chunk of the patch out, if you like.
>  
I now understand:
o mpicxx.h contains the C++ interface to MPI.
o Pooma does not use this MPI interface.

I am confused about LAM and gcc 2.95 since I sometimes use LAM with gcc 
3.x.y.  If your problem goes away by using gcc 3.4 with LAM, let's omit 
this special-purpose code and commit the rest of this patch.  Otherwise, 
the entire patch is fine.

> Richard.
>
>  
>
> > > ------------------------------------------------------------------------
> > >
> > > Index: SerialAsync.h
> > > ===================================================================
> > > RCS file: 
> > > /home/pooma/Repository/r2/src/Threads/IterateSchedulers/SerialAsync.h,v
> > > retrieving revision 1.11
> > > diff -u -u -r1.11 SerialAsync.h
> > > --- SerialAsync.h       8 Jan 2004 21:45:49 -0000       1.11
> > > +++ SerialAsync.h       16 Aug 2004 19:22:33 -0000
> > > @@ -72,6 +72,7 @@
> > > #include <stack>
> > > #include "Pooma/Configuration.h"
> > > #if POOMA_MPI
> > > +# define MPIPP_H  // prevent lam mpicxx.h from being included
> > > # include <mpi.h>
> > > #endif
> > >
> > >
> > >      
> > --
> > Jeffrey D. Oldham
> > address@hidden
> >
> >    
>
> --
> Richard Guenther <richard dot guenther at uni-tuebingen dot de>
> WWW: http://www.tat.physik.uni-tuebingen.de/~rguenth/
>
>  


--
Jeffrey D. Oldham
address@hidden