is that a problem? Depending on your kernel your (systemtime) clock may tick 1000, 300, 250 or 100 times a second.
And in addition to those there will be network adapter, disk and other devices interrupt.
rdate is a Linux command and the network time protocol for immediate date and time setup from another machine. The clocks are synchronized by entering rdate with the -s switch (command without switch just checks the time but does not set anything).