top command shows the process cpu utilization, and it when we sum the cpu utilization of all the processes then it goes greater than 100%. And how can it shows the cpu utilization of each process( app. > 300 process) in very short span of time. There is a question [about cpu usage by a process] : http://stackoverflow.com/questions/1420426/calculating-cpu-usage-of-a-process-in-linux that tells us to sleep for 1 second. And according to that solution Cpu usage by a process is different from top command output. so please tell me about right solution. My computer has the configuration Intel core2duo and ubuntu 10.10.