I’m always trying to find a good method of monitoring system performance and logging it, but today I ran into a rather strange issue that I couldn’t find on google.

sar 0 was returning high idle percentages:

# sar -u 0

08:17:29 AM       CPU     %user     %nice   %system   %iowait     %idle

08:17:29 AM       all     18.11      0.01     11.66     70.22    3549.42
running top didn't produce 3.5k % idle and in fact the system was nearly 98% idle. 
The quick fix is to simply run

yum update sysstat
That fixed the problem immediately on the box I was using.

Hope this helps someone else.