[Cialug] user vs. sys cpu time

[Kendall Bailey]

I have a math optimization app that runs for several minutes on a dual
proc/dual core opteron SLES 9 box.  Plenty of RAM.  It uses 4 threads
to do some parallel computation to take advantage of all 4 cpu cores.
Looking at 'top', or using 'time' to measure cpu time, it's logging
30% or more sys time vs. 60-70% user time during the parallel phases.
I ran it with 'strace -c' and that says only 0.003 seconds are spent
in system calls.  No system calls going on at all on the 4 threads.
So what does the 'sys' time represent as reported by top?

Thanks.
Kendall