[Mpi3-rma] Next RMA Telecon

[Torsten Hoefler]

Hello Again,

I created ticket #308 and #309 (I'm not 100% convinced by #309). Please
comment as appropriate. 

https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/308
https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/309

I also removed win_lock_all(exclusive) from #284.

https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/284

I also talked to Marc and he explained that the idea was that the lock
can essentially be implemented as nonblocking (blocking at first use).
However, together with local buffering (the first n puts may be
nonblocking and the n-th put may block after the buffer is exhausted),
this could create arbitrary blocking RMA operations (from a user's
perspective). Marc agreed that this may be hard to program. So this
functionality was clearly intended but the consequences may not be and
this issue may need to be fixed.

He will look into this in detail and get back to us.

Thanks & Best,
  Torsten

> The telecon ended after 1.5 hours and I'm summarizing our discussions
> and decisions below:
> 
> > 1) Adam's suggestion that datatype offsets have to be relative to MPI_BOTTOM    
> - Torsten creates a ticket to remove this sentence
> 
> > 2) disp_unit should not be fixed (one can create one window for each)           
> - this issue was resolved and the comment will be ignored by Adam's
>   advice
> 
> > 3) allocate_shared proposal with MPI_Win_lock_all(exclusive)                    
> - remove MPI_Win_lock_all(exclusive) from the proposal and re-read
> 
> > 4) ticket 300: https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/300          
> - Torsten will talk to Marc and report back
> 
> > 5) ticket 283: https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/283          
> - Jim will bring a full proposal forward
> 
> > 6) Adam suggested: p23, 6-7 Regarding status, we should either say that         
> >    all fields are undefined (except for the error) or we should specify         
> >    all values, e.g., what about values returned for MPI_GET_COUNT,              
> >    MPI_GET_ELEMENTS, or MPI_TEST_CANCELLED? Replace "The values of the          
> >    MPI_SOURCE and MPI_TAG fields are undefined." with "All other fields         
> >    in status are undefined." -- Question: Would it be useful to set             
> >    fields for count and get elements?                                           
> - Torsten will create a ticket to clarify that everything that is not
>   explicitly specified remains undefined (similar to I/O)
> 
> Comments are welcome!
> 
> Thanks & Best,
>   Torsten
> 
> -- 
>  bash$ :(){ :|:&};: --------------------- http://www.unixer.de/ -----
> Torsten Hoefler         | Performance Modeling and Simulation Lead
> Blue Waters Directorate | University of Illinois (UIUC)
> 1205 W Clark Street     | Urbana, IL, 61801
> NCSA Building           | +01 (217) 244-7736
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-- 
 bash$ :(){ :|:&};: --------------------- http://www.unixer.de/ -----
Torsten Hoefler         | Performance Modeling and Simulation Lead
Blue Waters Directorate | University of Illinois (UIUC)
1205 W Clark Street     | Urbana, IL, 61801
NCSA Building           | +01 (217) 244-7736