Hello Jeff: On Fri, Dec 12, 2008 at 08:37:14AM -0500, Jeff Squyres wrote:
> FWIW, Open MPI does have on its long-term roadmap to have "blocking" > progress -- meaning that it'll (probably) spin aggressively for a > while and if nothing "interesting" is happening, it'll go into a > blocking mode and let the process block in some kind of OS call. > > Although we have some interesting ideas on how to do this, it's not > entirely clear when we'll get this done. There's been a few requests > for this kind of feature before, but not a huge demand. Please count me as wanting that feature. And it would be nice - for our application - to block immediately. > This is probably because most users running MPI jobs tend to devote > the entire core/CPU/server to the MPI job and don't try to run other > jobs concurrently on the same resources. Our situation is different. While our number-cruncher application is running, we would like to be able to do some editing, compiling, post-processing. I once ran three jobs, hence 6 processes, on our 4-cpu system, and was unable to ssh into the machine. Or maybe I did not wait long enough... The number-cruncher has two processes, and each needs intermediate results from the other, inside a do i=1,30000 enddo As I mentioned earlier, most of the time, only one process is executing, and the other is waiting for results. My guess is that, with the blocking feature you describe, I could double the number of number-cruncher jobs running at one time, thus doubling throughput. Regards, Douglas. -- Douglas Guptill Research Assistant, LSC 4640 email: douglas.gupt...@dal.ca Oceanography Department fax: 902-494-3877 Dalhousie University Halifax, NS, B3H 4J1, Canada
