I am trying to understand the large amount of allocated memory that seems not to be accounted for.
I'll say up front that I am discussing memory usage without cache and buffers, 'cause I know that misunderstanding comes up a lot.

I am in a KDE 4.3 desktop, using a number of java apps that tend to eat up a lot of memory.
after a few days, even if I quit most apps, 1 gb of ram remains allocated (out of 2 gb).
this appeared excessive, and I took the time to add up all values of the RES column in htop (for all users).
the result was about 1/2 gb.

am I trying to match the wrong values?
or could some memory be allocated and not show up in the process list?

any suggestion will be greatly appreciated


this is the output of free
Code:
             total       used       free     shared    buffers     cached
Mem:       2055456    1940264     115192          0     123864     702900
-/+ buffers/cache:    1113500     941956
Swap:      2104504     246416    1858088
this is the topmost output from top
Code:
top - 12:31:00 up 4 days,  1:24,  2 users,  load average: 0.06, 0.06, 0.01
Tasks: 175 total,   1 running, 174 sleeping,   0 stopped,   0 zombie
Cpu(s):  0.4%us,  0.2%sy,  0.0%ni, 99.3%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:   2055456k total,  1931376k used,   124080k free,   123624k buffers
Swap:  2104504k total,   247068k used,  1857436k free,   698888k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
 2041 michele   20   0  401m  11m 6388 S    1  0.6   1:33.15 yakuake
 2047 michele   20   0  591m  42m  18m S    1  2.1   5:50.41 kopete
 1040 root      20   0  503m 117m 3960 S    0  5.9  74:23.69 Xorg
 1914 michele   20   0  657m  31m  13m S    0  1.6  51:09.98 kwin
 1918 michele   20   0  878m  49m  24m S    0  2.5  30:32.75 plasma-desktop
16882 michele   20   0 19132 1380  980 R    0  0.1   0:00.05 top
    1 root      20   0 19456 1320  784 S    0  0.1   0:02.38 init