help me understand memory usage

[javatwo]

On Linux FC 6. The machine physical memory is 4G.

After machine reboot, start JBoss and deploy application, the total memory usage is about 700M. After running JBoss for several hours, the memory used is increased to 3.5G.

$ ps -eo rss

Adding all used memory up, the total is about 580M. where does the rest memory go?

$ top
Tasks: 95 total, 2 running, 93 sleeping, 0 stopped, 0 zombie
Cpu(s): 0.0%us, 0.1%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.2%hi, 0.0%si, 0.0%st
Mem: 4037992k total, 3456532k used, 581460k free, 626264k buffers
Swap: 10223608k total, 0k used, 10223608k free, 2119340k cached

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
12529 root 25 0 2502m 388m 43m S 0 9.9 1:27.33 java
2584 root 15 0 326m 114m 3596 S 0 2.9 1491:46 yum-updatesd
2404 mysql 15 0 246m 26m 4236 S 0 0.7 1:28.03 mysqld

the JBoss (java): 388M.

Please help me.
Thanks
Dave

[peterj]

Looks like java has 2.5GB of virtual memory allocated. This implies to me that there is a memory leak somewhere, possibly in your application. I suggest using -verbose:gc to analyze the memory usage.