How to measure throughput in MongoDB
The mongostat tool provides you with this information.

Example output of mongostat:

insert query update delete getmore command dirty used flushes vsize   res qrw arw net_in net_out conn     set repl                time
*0     2     *0     *0       0     2|0  0.0% 0.0%       0 3.18G 16.0M 0|0 1|0   556b   57.2k    2 replset  PRI May 22 09:17:02.431


From the example above, the query field has the value of 2. This means that at that moment in time, the system processes two queries per second.

For full description of the output fields of mongostat, please see the Fields section.