On Jun 4, 2010, at 2:18 PM, Katz, Jacob wrote: > This would be a quite serious limitation from my point of view. I'm a library > developer, and my library is used in heterogeneous environment. Since 32b > executables regularly work on 64b machines, they get intermixed by the users > with 64b executables on the same machine. Switching to another BTL would > incur serious performance issues...
You're really the first person to ask us for combined 32/64 bit *on the same machine*. Just curious -- why would people still be compiling in 32 bit mode these days? > I noticed an SM bug report that looks similar to mine and was reportedly > fixed in 1.4.2. I'm going to check that version. If it still fails, what > would be the effort to fix this? No, that was for a different issue (32/64 bit *across different machines*) -- it won't fix this sm issue. I doubt that any of us had really even thought about mixing 32/64 bit in the sm BTL before (I know I hadn't). Indeed, we haven't had much demand for 32 bit support over the past few years (it's non-zero, but not large). We try to guide OMPI's development by customer demand for features and platforms to support. Although not a definitive measure, having only one person ask for a (potentially difficult to implement) feature is a good indicator that that's a feature only wanted/needed by a small number of users. FWIW, the 32/64 scenarios we've generally seen before have been for running an MPI job across multiple different flavors of hardware or OSs -- but we haven't seen much of that, either. All that being said, I'm *not* any kind of authoritative source of HPC knowledge that knows what every customer is doing -- for example, you obviously have a different perspective and viewpoint than me. Can you give some kind of quantification about how important this kind of feature is to the general HPC community? How many applications / users do this? Do you know if other MPI implementations support it? -- Jeff Squyres jsquy...@cisco.com For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/
