[Flounder] VPS performance

[DL Neil]

I am wondering if the performance of a couple of my (European) VPSes
have (consistently) degraded in recent times.

There may be many reasons. Some related to work-load (which hasn't
really changed, ignoring the vagaries of email transactions and
web-visitors). The ones that concern are related to the
service-provider's fabric - yet not wishing to blame them for issues on
the Internet between 'here' and 'there'...

What tool(s) do you use to monitor and record response-time, eg several
times per day, over months?
-- 
Regards,
=dn