Good to know that I'm not just not finding the solution, there simply is none. The system is actually dedicated to the job. But the process may, while working, receive a signal that alters the ongoing job. Like for example a terminate signal or more data to be taken into consideration. That's why I need to listen in parallel and a CPU core less troublesome. Thanks, Murat
George Bosilca schrieb: > Currently there is no work around this issue. We consider(ed) that > when you run an MPI job the cluster is in dedicated mode, so a 100% > CPU consumption is acceptable. However, as we discussed at our last > meeting, there are others reasons to be able to yield the CPU until a > message arrives. Therefore, we plan to have a blocking mode in the > near future. The is no timeframe for this, but the discussions already > started (that is usually a good sign). > > Thanks, > george. > > On Oct 23, 2007, at 9:17 AM, Murat Knecht wrote: > >> Hi, >> thanks for answering. Unfortunately, I did try that, too. The point >> is that i don't understand the ressource consumption. Even if the >> processor is yielded, it still is busy waiting, wasting system >> resources which could otherwise be used for actual work. Isn't there >> some way to activate an interrupt mechanism, so that the wait/recv >> blocks the thread, e.g. puts it to sleep, until notified? >> >> Murat >> >> Tim Mattox schrieb: >>> You should look at these two FAQ entries: >>> http://www.open-mpi.org/faq/?category=running#oversubscribing >>> http://www.open-mpi.org/faq/?category=running#force-aggressive-degraded >>> To get what you want, you need to force Open MPI to yield the >>> processor rather than be aggressively waiting for a message. On >>> 10/23/07, Murat Knecht <murat.kne...@student.hpi.uni-potsdam.de> wrote: >>>> Hi, Testing a distributed system locally, I couldn't help but >>>> notice that a blocking MPI_Recv causes 100% CPU load. I deactivated >>>> (at both compile- and run-time) the shared memory bt-layer, and >>>> specified "tcp, self" to be used. Still one core busy. Even on a >>>> distributed system I intend to perform work, while waiting for >>>> incoming requests. For this purpose having one core busy waiting >>>> for requests is uncomfortable to say the least. Does OpenMPI not >>>> use some blocking system call to a tcp port internally? Since i >>>> deactivated the understandably costly shared-memory waits, this >>>> seems weird to me. Someone has an explanation or even better a fix >>>> / workaround / solution ? thanks, Murat >>>> _______________________________________________ users mailing list >>>> us...@open-mpi.org http://www.open-mpi.org/mailman/listinfo.cgi/users >> _______________________________________________ >> users mailing list >> us...@open-mpi.org >> http://www.open-mpi.org/mailman/listinfo.cgi/users > > ------------------------------------------------------------------------ > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users
