For two-sided Open MPI uses CMA, XPMEM, or KNEM for single-copy shared
memory if available. Otherwise it does two copies.
-Nathan
On Mon, Apr 11, 2016 at 09:02:38AM -0700, Jeff Hammond wrote:
>MPI-3 shared memory gives you direct access, meaning potentially zero
>copies if you eg just
MPI-3 shared memory gives you direct access, meaning potentially zero
copies if you eg just read shared state.
Optimizing intranode MPI comm just reduces copies. Since MPI comm semantics
require one copy, you can't do better in RMA. In Send-Recv, I guess you can
do only one copy with a CMA
Hello,
I have been looking into the MPI-3 extensions that added ways to do
direct memory copying on multi-core 'nodes' that share memory.
Architectures constructed from these nodes are universal now, so
improved ways to exploit them are certainly needed. However, it is my
understanding that
