I don't need your branch because 1) we are not doing any communication in this VecAssembly and I added the IGNORE stuff just to make sure and 2) we are catching load imbalance from another part of the code, I am now sure. I can now see that VecAssemblyBegin's timers do not report this type of load imbalance because it starts with a synch. This is what I suspected but I was wondering why the timers did not report this load imbalance. On Fri, May 29, 2015 at 11:12 AM, Jed Brown <[email protected]> wrote:

Mark Adams <[email protected]> writes:

...

Thanks, this code does not have any communication in VecAssembly so I added the INGNORE stuff and added a barrier before this section of code. I am suspecting that VecAssembly is catching load imbalance but not reporting it for some reason.

If you put a barrier before, it starts at about the same time on all processes. The operation contains synchronization followed by (scalable) point-to-point messaging. The slowness is almost certainly caused by the non-scalable algorithm -- I've seen it with other applications. So try my branch.