Performance monitoring on Linux

There are some built in command in Linux to check the performance of linux eg

• top : Provide information (frequently refreshed) about the most CPU-intensive processes currently running. you can sort by CPU% or MEM% by typing 'F'
• ps -aux : all the processes in the system. use "grep "to filter which processes
• free : Display statistics about memory usage: total free, used, physical, swap, shared, and buffers used by the kernel.Easy monitoring with "SAR"

The SAR suite of utilities is bundled with your system (in fact, it is installed on most flavors of UNIX®), but probably not enabled. To enable SAR, you must run some utilities at periodic intervals through the cron facility. Use the crontab -e command while running as the root user

• mpstat : average CPU statistic
• iostat : flow of data to and from disk drive
• vmstat : memory, like "free"

Useful link

http://www-128.ibm.com/developerworks/aix/library/au-unix-perfmonsar.html