I know it depends and I want to know exactly what is the dependency and general complexity analysis.
Is it really no documentation at all ? For example you said "to be replaced soon", then what is the algorithms that will be used to replace ? Is there any publication available ? In another words, how do you know they will be replaced by which algorithm, please teach me !
On Aug 23, 2011, at 3:32 AM, Hoang-Vu Dang wrote:Unfortunately, you probably won't.
> Where could I find a detailed documentation about algorithms that has been using in Open MPI ?
All of OMPI's collectives are implemented as plugins under the ompi/mca/coll/ tree. There are several different plugins in that tree -- each one has its own directory (with the exception of "base", which is glue code for the whole collective algorithm framework).
> For example, I would like to answer following questions: how MPI_Algather operation is done? what is the complexity in term of the number of data send/receive given a number of node involved? what is the data structure behind ?. Same as for MPI_Alreduce etc..
You probably want to look in the "tuned" component for OMPI's current-generation algorithms (to be replaced soon, but that's what's mostly used today). "tuned" has many different algorithm implementations for each MPI collective, and uses sophisticated run-time checking to determine which to use.
So the answer to your original query -- how is the MPI_Allgather operation done? -- is, "it depends" on things like message size, number of peers, etc. :-)
For corporate legal information go to:
users mailing list