Disclosed is a method for calculating clock offset and skew between two
clocks in a computer system. The method comprises the steps of sending
data packets from a first processing unit in the computer system to a
second processing unit in the computer system, and sending the data
packets from the second processing unit to the first processing unit.
First, second, third and fourth time stamps are provided to indicate,
respectively, when the packets leave the first processing unit, arrive at
the second processing unit, leave the second processing unit, and arrive
at the first processing unit. The method comprises the further steps of
defining a set of backward delay points using the fourth time stamps, and
calculating a clock offset between clocks on the first and second
processing units and clock skews of said clocks using said set of
backward delay points.