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Subject: Re: [OMPI users] OpenMPI collective algorithm selection
From: Ralph Castain (rhc_at_[hidden])
Date: 2013-04-05 09:11:51


You can get the headers installed by adding --with-devel-headers to the configure line.

On Apr 5, 2013, at 5:10 AM, chandan basu <cbasu_at_[hidden]> wrote:

> Hi,
>
> I want to use OpenMPI dynamic collective algorithm selection using rules file, e.g.
>
> mpirun --mca coll_tuned_use_dynamic_rules 1 --mca_coll_tuned_dynamic_rules_file rules.txt ./myexe
>
> I can see some examples in earlier discussions (given below). My question is how do I know the ID for the different collectives. I do not see coll_tuned.h in the installation folder . Is there any command to find the ID of an algorithm. I am particularly interested in Alltoallv. I have checked that coll_tuned_alltoallv_algorithm 1 and coll_tuned_alltoallv_algorithm 2 has lot of performance difference depending on data size and comm size. So I think giving a rules file can improve the performance over a range of data sizes and comm size. Any help in this regard will be appreciated.
>
> With regards,
>
> -Chandan
> ----------------------------------------
> Dr. Chandan Basu
> National Supercomputer Center
> Linköping University
> S-581 83 Linköping
> email: cbasu_at_[hidden]
> -----------------------------------------
> >1 # num of collectives
> >3 # ID = 3 Alltoall collective (ID in coll_tuned.h)
> >2 # number of com sizes
> >1 # comm size 1
> >1 # number of msg sizes 1
> >0 1 0 0 # for message size 0, linear 1, topo 0, 0 segmentation
> >8 # comm size 8
> >4 # number of msg sizes
> >0 1 0 0 # for message size 0, linear 1, topo 0, 0 segmentation
> >32768 2 0 0 # 32k, pairwise 2, no topo or segmentation
> >262144 1 0 0 # 256k, use linear 1, no topo or segmentation
> >524288 2 0 0 # message size 512k+, pairwise 2, topo 0, 0 segmentation
> ># end of first collective
>
>
> --
>
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