unix memory question

[jim martin]

Hi.. I am curious to know how unix define memory usage.  When I type "free" or top, I saw the used
memory is so much as shown below.  But my server is actually idle.  In the top's process show that
the highest memory usage process is only taking up 0.5%. why? the Free command shows used memory
is so much?

[root at wat]# free
     total  used    free   shared  buffers   cached
Mem: 1027344 922496 104848   0     124304     589148

-/+ buffers/cache:     209044     818300
Swap:      2031608          0    2031608


Besides, I heard from my friend that there is a method to allocate memory for different process.
For example 30% for apache and 40% for tomcat. Is that true? How to do it?





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