top-11:08:05up4days,23:44,2users,load...
top - 11:08:05 up 4 days, 23:44, 2 users, load average: 1.36, 1.64, 1.66
Tasks: 208 total, 1 running, 207 sleeping, 0 stopped, 0 zombie
Cpu(s): 4.6 us, 0.2 sy, 0.0 ni, 93.9 id, 1.2 wa, 0.0 hi, 0.0 si, 0.0 st
Mem: 99197364 total, 98823192 used, 374172 free, 285196 buffers
Swap: 2096444 total, 340340 used, 1756104 free, 88502180 cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
26517 rabbitmq 20 0 1170m 557m 2104 S 8 0.6 1913:21 beam.smp
26054 root 20 0 167m 27m 2112 S 86 0.0 1380:07 carbon-cache.py
22021 admin 20 0 329m 6416 2328 S 43 0.0 82:25.90 amqp2mongodb
21987 admin 20 0 6709m 1.2g 9860 S 8 1.2 14:11.05 java
21954 admin 20 0 2553m 854m 9796 S 7 0.9 12:59.37 java
2064 root 20 0 0 0 0 S 0 0.0 30:24.41 flush-8:0
19281 root 20 0 0 0 0 S 0 0.0 0:01.20 kworker/0:2
26001 root 20 0 0 0 0 S 0 0.0 4:26.89 jbd2/sda8-8
24301 mongodb 20 0 497g 92g 87g S 100 97.5 997:37.46 mongod
1 root 20 0 10636 708 676 S 0 0.0 0:06.42 init
2 root 20 0 0 0 0 S 0 0.0 0:00.07 kthreadd
在以上top输出界面，如果要按照内存使用量排序，要按哪个键
