My coworkers and I share an 8-core server running Ubuntu for our batch processes. I tend to run 4 processes at a time, each of which consumes 100% CPU per core when nothing else is running. When a coworker runs his processes (typically about 4 at a time), his also get 100% per. However, when both of us run ours (he always goes first), his still get 100% and mine seem to divide the remaining processing power and linger in the 10-40% range. I even reniced his process to a lower value and it did not change. What are the issues that may cause this?
A:
I haven't a clue what might be causing it but you may be able to bypass the issue completely or at least get some more information by using the 'taskset' command to constrain your coworker's processes to the first four processors and yours to the last four.
If you still see the same percentage breakdowns, you'll at least have eliminated priority & scheduling contention between the two process groups as the source of the problem.
Rakis
2010-04-15 17:27:34