Command to check for Memory i.e locked but not used

ipcs -ma

IPC status from /dev/mem as of Fri Oct 21 13:07:00 CEST 2011
T        ID     KEY        MODE       OWNER    GROUP  CREATOR   CGROUP NATTCH     SEGSZ  CPID  LPID   ATIME    DTIME    CTIME
Shared Memory:
m   1048578 0x0d01036f --rw-rw----     root   system     root   system      2      1440 299196 405584 11:05:04 12:24:46 11:46:12