In addition to what @argrullo posted, since your problem device seems to be a 3D appliance you will need to login via ssh and then switch to expert mode cli (Linux shell) to run "top".
Cisco Fire Linux OS v6.2.2 (build 11)
Cisco FirePOWER 7125 v6.2.2.1 (build 73)
Last login: Mon Mar 5 14:01:01 UTC 2018 on cron
> expert
admin@Sourcefire3D:~$ top
top - 14:10:59 up 110 days, 5:04, 1 user, load average: 0.87, 1.04, 1.03
Tasks: 155 total, 3 running, 152 sleeping, 0 stopped, 0 zombie
Cpu(s): 1.8%us, 4.0%sy, 0.0%ni, 94.2%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 15397552k total, 13777836k used, 1619716k free, 115684k buffers
Swap: 6012752k total, 479868k used, 5532884k free, 8350648k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
11266 root 20 0 3504m 257m 2920 S 14 1.7 18532:17 nfm_exceptiond
3815 root 0 -20 0 0 0 S 14 0.0 21652:23 nfemsg_c0e1/0
1097 sfsnort 20 0 3001m 707m 20m S 3 4.7 139:08.39 snort
1098 sfsnort 20 0 2991m 682m 20m S 3 4.5 103:34.12 snort
1096 sfsnort 20 0 3009m 774m 21m S 3 5.2 106:32.00 snort
1100 sfsnort 20 0 3019m 727m 20m S 3 4.8 93:01.36 snort
1099 sfsnort 20 0 2996m 698m 20m S 2 4.6 82:43.63 snort
<remaining output omitted>
