When we calculate metrics like msg/sec, latency, etc
we expect the start and end time as time of
the first and last processed message:
RPC Server life timeline:
[----0..5 sec----][---5..10 sec---][---10..15 sec--]
waiting clients 10 msg recved wait sigint
expected: duration 5 sec, 2 msg/sec
actual (incorrect): duration 15 sec, 0.6 msg/sec
no reason to set the boundaries if server was idle few seconds
before running of clients and after.
Change-Id: I33e0a605b54ea7b89977504892528c41c3b00a68
6a41a81c9e