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Hi,
	I'm reading Operating System Concepts (7th Edition) , Written by
Abraham , Peter & Greg.

	In chapter 5.3 , it talks about a schedule algorithm: SJF
	SJF means shortest jobs schedules firstly.

	To compare different process , thy use a process running time.

	e.g
		P1 takes 6 secs to run
		P2 takes 3 seconds
		P3 takes 10 secs

	Then we should put those tasks in array like this:
	P2 => P1 => P3

	That looks much reasonable , but my question is , how does an OS know
that a process will takes longer time to finish its life ?
	I think it's impossible to let OS know exactly how long a process will
take to run.


	So far in my experience , i think there's a few ways to compare
Process running time:

	Forgive me if i have a poor experience on OS ;-)

	I) Number of Loops in a Program , can be detected by compiler
	As long as you have any loops , you are slower than any straight ahead
program

	II) Length of Program , longer code takes longer time sometimes , not a
good way.


	Anyone wants to share some experience with me ?

	Be very glad to hear your voice ;-)



- -- 
Best Regards,
Aaron Lewis - PGP: 0x4A6D32A0
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