Is there a way to specify collective depending on the size of the message and number of processes?
Regards, Pavel Mezentsev 2012/4/3 George Bosilca <bosi...@eecs.utk.edu> > Roswan, > > There a re simpler solutions to achieve this. We have a built-in mechanism > to select a specific collective implementation. Here is what you have to > add in your .openmpi/mca-params.conf (or as MCA argument on the command > line): > > coll_tuned_use_dynamic_rules = 1 > coll_tuned_bcast_algorithm = 6 > > The first one activate the dynamic selection of collective algorithms, > while the second one force all broadcast to be of the type 6 (binomial > tree). Btw, once you set the first one, do a quick "ompi_info --param coll > tuned" to see the list of all possible options for the collective algorithm > selection. > > george. > > On Apr 2, 2012, at 23:10 , roswan ismail wrote: > > Hi all.. > > I am Roswan Ismail from Malaysia. I am focusing on MPI communication > performance on quad-core cluster at my university. I used Open MPI-1.4.3 > and measurements were done using scampi benchmark. > > As I know, open MPI used multiple algorithms to broadcast data (MPI_BCAST) > such as binomial, pipeline, binary tree, basic linear and split binary > tree. All these algorithms will be used based on message size and > communicator size. For example, binomial is used when message size to be > broadcasted is small while pipeline used for broadcasting a large message. > > What I want to do now is, to use fixed algorithm i.e binomial for all > message size. I want to see and compare the results with the default > results. So, I was modified coll_tuned_decision_fixed.c which is located in > open mpi-1.4.3/ompi/mca/coll/tuned by returning binomial algorithm for all > condition. Then I recompile the files but the problem is, the results > obtained is same as default. It seems I do not do any changes to the codes. > > So could you guys tell me the right way to do that. > > Many thanks > > ** > *Roswan Binti Ismail, > FTMK, > Univ. Pend. Sultan Idris, > Tg Malim, Perak. > Pej: 05-4505173 > H/P: 0123588047 > iewa...@gmail.com <iewanis1402@hotmail> > ros...@ftmk.upsi.edu.my > *** > _______________________________________________ > devel mailing list > de...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/devel > > > > _______________________________________________ > devel mailing list > de...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/devel >
