> From: Rob Ross <rross@mcs.anl.gov>
>
> Should we consider this as interest in working on this problem on
> the IBM side :)? -- Rob

Say what?! ;)

Meaning we can get rid of all o(p) allocations?  Not sure how you do internal collectives on behalf of the app/mpi-io without at least some of those.  I was looking more for agreement that collective i/o is 'what it is'... and maybe some idea if we just have some known limitations on scaling it.  Yes, that BG alltoallv is a bigger problem that we can avoid with an env var -- is that just going to have to be 'good enough'?  (I think that Jeff P wrote that on BG/P and got good performance with that alltoallv.  Trading memory for performance, not unusual, and at least it's selectable.)