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Subject: [OMPI devel] algorithm selection in open mpi
From: roswan ismail (iewanis_at_[hidden])
Date: 2012-04-02 23:10:46

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 iewanis_at_[hidden] roswan_at_[hidden]