Note that the availability is somewhat affected by the time it takes to reboot the system after a crash has been discovered. Availability of NCSA's Convex Exemplar Systems System Month Total Hours Hrs. If there is more than one process in a sub-complex and the number of runable threads is greater than the number of CPU's the CPU will be shared. Each process has a scheduling priority which it inherits from its parent and each thread within the process also has a scheduling priority which it obtains from the process's scheduling priority. A process can change its scheduling priority and the scheduling priority of all its threads, but a thread cannot change its sheduling own scheduling priority to something different.
All threads use timeshare scheduling unless the sub-complex is setup to use fixed priority.
There are no low level routines available for the user. So, if your subcomplex does not cross a hypernode, then an a.out run on that subcomplex will get its global memory from the global memory defined on that hypernode only. Here the threads would be running on only 1 node, but their data would be spread across both nodes in the subcomplex. See the mpa man page for details. This way your a.out will have its data defined all on 1 node even though the subcomplex spans nodes.