scalability issue in `ssg_group_observe`
I have added timing to the
ssg-observe-group.c test to time how long it takes to observe an ssg group for varying numbers of processes. I am collecting timings on all MPI processes and then collecting the min, max, and average times to observe the group.
I am concerned that as the number of processes increases, the distribution of response times gets larger and larger. Notice that the min time is fairly consistent -- some process is indeed observing the group nice and speedy-like. The max time grows, as does the average time.
This distribution of timing suggests to me that something is serializing the observe request.