List of commands that can be used for monitoring performance :
cron Process scheduling
nice/renice Change priorities
setpri Set priorities
netstat Network statistics
nfsstat NFS statistics
time/timex Process CPU Utilization
uptime System Load Average
ps Process Statistics
iostat BSD tool for I/O
sar Bulk System Activity
vmstat BSD tool for V. Memory
gprof Call Graph profiling
prof Process Profiling
trace Used to get more depth
tprof CPU Usage
svmon Memory Usage
filemon Filesystem, LV .. activity
netpmon Network resources
