I would advise pre-posting MPI_Irecv's if you know that messages will be coming.
Barriers should only be used if you need to synchronize between groups of processes. Keep in mind that MPI is a lossless/reliable message delivery mechanism, so there's no need for you to call additional error-correcting API functions to ensure that you get all the messages that were sent. Additionally, Iprobe is typically only useful if you don't know the size / sender of the message. Calling Iprobe almost guarantees that MPI will need to make an internal copy of the message. So avoid probe / iprobe if you can. On Jun 28, 2010, at 5:16 PM, amjad ali wrote: > I guess that if the receiver want to ensure that the sender should send data > only when the receiver will be able/free to receive data, > > then use MPI-Barriers. > > > > On Mon, Jun 28, 2010 at 12:53 PM, David Zhang <solarbik...@gmail.com> wrote: > Use MPI_Iprobe. It's a nonblocking probe that allow you to see if a message > is coming. So in your receiver code you just periodically probe to see if > messages are coming your way. > > > On Sun, Jun 27, 2010 at 9:11 PM, Jack Bryan <dtustud...@hotmail.com> wrote: > thanks > > I know that. > > MPI_irecv() ; > > do other works; > > MPI_wait(); > > But, my message receiver is much slower than sender. > > when the sender is doing its local works, the sender has sent out their > messages. but at this time, > the sender is very busy doing its local work and cannot post MPI_irecv to get > the messages from > senders. > > Any help is appreciated. > > jack > > > > From: jiangzuo...@gmail.com > Date: Mon, 28 Jun 2010 11:55:32 +0800 > > To: us...@open-mpi.org > Subject: Re: [OMPI users] openMPI asychronous communication > > OK, then i think you also know using MPI_Wait to wait the asynchronous > requests to complete. if sender works faster then receiver(or reverse), then > the MPI_Wait will do wait, not just deallocted. you should keep the buffer > content before MPI_Wait. > > Changsheng Jiang > > > On Mon, Jun 28, 2010 at 11:41, Jack Bryan <dtustud...@hotmail.com> wrote: > thanks > > I know this. > > but, what if sender can send a lot of messages to receivers faster than what > receiver can receive ? > > it means that sender works faster than receiver. > > Any help is appreciated. > > jack > > > From: jiangzuo...@gmail.com > Date: Mon, 28 Jun 2010 11:31:16 +0800 > To: us...@open-mpi.org > Subject: Re: [OMPI users] openMPI asychronous communication > > > MPI_Isend - Starts a standard-mode, nonblocking send. > > BTW, are there any asynchronous collective operations? > > Changsheng Jiang > > > On Mon, Jun 28, 2010 at 11:22, Jack Bryan <dtustud...@hotmail.com> wrote: > Dear All: > > How to do asychronous communication among nodes by openMPI or boot.MPI in > cluster ? > > I need to set up a kind of asychronous communication protocol such that > message senders and receivers can communicate asychronously without losing any > messages between them. > > I do not want to use blocking MPI routines because the processors can do other > operations when they wait for new messages coming. > > I donot find this kind of MPI routines that support this > asychronous communication. > > Any help is appreciated. > > thanks > > Jack > > June 27 2010 > > The New Busy think 9 to 5 is a cute idea. Combine multiple calendars with > Hotmail. Get busy. > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users > > > The New Busy think 9 to 5 is a cute idea. Combine multiple calendars with > Hotmail. Get busy. > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users > > > The New Busy think 9 to 5 is a cute idea. Combine multiple calendars with > Hotmail. Get busy. > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users > > > > -- > David Zhang > University of California, San Diego > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users -- Jeff Squyres jsquy...@cisco.com For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/
