It seems that the kernel time is not monotonically increasing in recent
(i386) kernels.
2.1.126 introduced a bug that is still present in 2.1.129. Code that
records the time during the top half of an interrupt may get a timestamp
that is exactly 10000 microseconds back in time from when it should be.
An easy way to see this is to use tcpdump on a reasonably busy network
(500 to 100 packets per second), and examine the usec portion of the
packet timestamp. This is affected because the timestamp is recorded
during interrupt time (netif_rx in linux/net/core/dev.c).
See this URL for more details and graphs:
http://atm.cs.waikato.ac.nz/~sfd/bug/
Stephen.
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Stephen Donnelly (BCMS) email: sfd@cs.waikato.ac.nz
Waikato ATM Group Lab G1.31 phone +64 7 838 4466 x6728
Computer Science Department, University of Waikato, New Zealand
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