This is the output of free -m on a production database (MySQL with machine. 83MB looks pretty bad, but I assume the buffer/cache will be used instead of Swap?
[admin@db1 www]$ free -m
total used free shared buffers cached
Mem: 16053 15970 83 0 122 5343
-/+ buffers/cache: 10504 5549
Swap: 2047 0 2047
top ouptut sorted by memory:
top - 10:51:35 up 140 days, 7:58, 1 user, load average: 2.01, 1.47, 1.23
Tasks: 129 total, 1 running, 128 sleeping, 0 stopped, 0 zombie
Cpu(s): 6.5%us, 1.2%sy, 0.0%ni, 60.2%id, 31.5%wa, 0.2%hi, 0.5%si, 0.0%st
Mem: 16439060k total, 16353940k used, 85120k free, 122056k buffers
Swap: 2096472k total, 104k used, 2096368k free, 5461160k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
20757 mysql 15 0 10.2g 9.7g 5440 S 29.0 61.6 28588:24 mysqld
16610 root 15 0 184m 18m 4340 S 0.0 0.1 0:32.89 sysshepd
9394 root 15 0 154m 8336 4244 S 0.0 0.1 0:12.20 snmpd
17481 ntp 15 0 23416 5044 3916 S 0.0 0.0 0:02.32 ntpd
2000 root 5 -10 12652 4464 3184 S 0.0 0.0 0:00.00 iscsid
8768 root 15 0 90164 3376 2644 S 0.0 0.0 0:00.01 sshd