[MPICH] IMB Exchange

[Rajeev Thakur]

You still need to call the Waitall though -- to deallocate the request
objects etc. 


> -----Original Message-----
> From: Calin Iaru [mailto:calin at dolphinics.no] 
> Sent: Friday, November 16, 2007 6:23 AM
> To: Rajeev Thakur
> Cc: mpich-discuss at mcs.anl.gov
> Subject: Re: [MPICH] IMB Exchange
> 
> Thanks Rajeev. It's certainly useful. So MPI_Waitall is not 
> actually needed.
> 
> Rajeev Thakur wrote:
> > It is ok to call the waitall after the receives. While 
> blocked in the 
> > receive, the MPI implementation will cause progress on other 
> > previously issued communication. It cannot just make 
> progress on the 
> > currently issued receive.
> >
> > Rajeev
> >
> >   
> >> -----Original Message-----
> >> From: owner-mpich-discuss at mcs.anl.gov 
> >> [mailto:owner-mpich-discuss at mcs.anl.gov] On Behalf Of Calin Iaru
> >> Sent: Thursday, November 15, 2007 6:01 AM
> >> To: mpich-discuss at mcs.anl.gov
> >> Subject: [MPICH] IMB Exchange
> >>
> >> I am looking at IMB Excahnge implementation which is:
> >>   - asynchronous send to left and right rank
> >>   - blocking receive from left and right
> >>   - Waitall
> >> What I don't understand is why is blocking receive followed by 
> >> Waitall.
> >> If all nodes are doing async send which are not guaranteed to 
> >> complete, then the receive operation is not satisfied. Let me know 
> >> your opinion. I would expect that waitall is after async send.
> >>
> >>
> >>     
> >
> >   
> 
>