Re: [OMPI users] libfabric verb provider for iWARP RNIC

On Apr 11, 2016, at 2:38 PM, dpchoudh . wrote: > > If the vendor of a new type of fabric wants to include support for OpenMPI, > then, as long as they can implement a libfabric provider, they can use the > OFI MTL without adding any code to the OpenMPI source tree itself.

Re: [OMPI users] libfabric verb provider for iWARP RNIC

Hi Howard and all Thank you very much for the information. I have a follow up question: If the vendor of a new type of fabric wants to include support for OpenMPI, then, as long as they can implement a libfabric provider, they can use the OFI MTL without adding any code to the OpenMPI source

Re: [OMPI users] resolution of MPI_Wtime

George Bosilca writes: > MPI_Wtick is not about the precision but about the resolution of the > underlying timer (aka. the best you can hope to get). What's the distinction here? (clock_getres(2) says "resolution (precision)".) My point (like JH's?) is that it doesn't

Re: [OMPI users] resolution of MPI_Wtime

Jeff Hammond writes: > George: > > Indeed, MPI_Wtick is not always a good measure of the precision of > MPI_Wtime. The way I would measure resolution is to call MPI_Wtime a few > million times. Is there typically a problem with just looping until the result changes a

Re: [OMPI users] What about MPI-3 shared memory features?

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

Re: [OMPI users] What about MPI-3 shared memory features?

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

[OMPI users] What about MPI-3 shared memory features?

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