Memory and Swap - Mailing list pgsql-admin

PostgreSQL 9.5.2

Linux Red Hat

I have 10 G of memory.  Nagios is saying I have 2 G used and 8 G free.

Yet my swap is at 1 G. 

1)      Why is that? 

2)      Over that past week it has climbed from almost nothing to 1 G.  It is a steady climb.  No big jump.

Thanks,

Lance