The code in UnixOperatingSystem.c used to calculate various CPU usage statics depends on out-of-date interpretation of various fields in /proc/stats that no longer hold true since Linux 2.6. This can result in issues like getSystemCpuLoad() reporting 100% CPU consumption for IO heavy loads.
Specifically, we should add irq and sirq to the system CPU time. And we should add IO wait, irq and sirq (all three new fields) to the total time. This is similar to what tools like top and sar do on Linux.