mongoDB memory usage crossing 100%

Question

During a load test i ran top command to check mongoDB resource usage. one fragment of the top command is:

top - 04:11:05 up 34 days, 21:33,  0 users,  load average: 2.38, 2.64, 2.76 

Tasks:   1 total,   0 running,   1 sleeping,   0 stopped,   0 zombie

Cpu(s): 16.4%us,  0.7%sy,  0.0%ni, 82.0%id,  0.0%wa,  0.0%hi,  0.9%si,  0.0%st

Mem:  41181112k total, 41060284k used,   120828k free,   118356k buffers

Swap: 14352376k total,   978988k used, 13373388k free, 30453168k cached

  PID   USER     PR   NI   VIRT  RES  SHR S %CPU   %MEM     TIME+       COMMAND                                                                                                    
 6894  mongod    15   0    108g  39g  39g S 24.3 **101.7** 233:44.52     mongod

Here mongoDB memory is crossing 100%. is this possible? because i didn't face mongoDB crash and Load test was successfully completed.

Answer 1

That number probably takes swap into account (the process didn't fit in main memory and was partially swapped out to disk).

used = 41060284 + 978988
total = 41181112

(used.to_f / total).round(2) # => 1.02