Re: [Boost-users] Hybrid parallelism, no more + mpi+serialization, many questions

On 16 Nov 2010, at 20:41, James C. Sutherland wrote:

On Tue, Nov 16, 2010 at 10:22 AM, Hicham Mouline wrote:

...

2. what are the pros/cons of loading the static data objects individually from each separate mpi process vs broadcasting the static data via MPI itself after only the master reads/sets up the static data?

It is easier to load them from disk on each process (you don't have to deal with serialization and passing the structure). Typically you will not see a performance problem if this is only a one-time startup cost and if you are not loading massive data files from a file system with weak IO capabilities onto very many MPI processes.

I would go with reading once and broadcasting, especially if, as was mentioned before, one aims at going to thousands of processes. No I/O system can scale, and implementing the broadcast is trivial: a single function call. Matthias