Lag, Ping Jitter, and Negative Pings

So my new machine rocks, but for some reason I start having problems with jitter in BZFlag. This is the weird jitter that makes the tanks jump around in time like a mexican jumping bean. I check my lag stats and sure enough... jitter in my ping times.

Ping time jitter is bad. Imagine that the server has a model of all the tanks and your computer has a similar model that is being synchronized to the server. If the time it takes a packet to get to your computer is some constant, then your view of the world will always be off by that offset -- some small lag.

Insert random changes in this offset and now packets arrive out of order and the tanks start stuttering like some sort of weird Star Trek time warp.

Tonight... a revelation... maybe I should check my server to see if it has the same problem, cause, well, we all know that Comcast is doing evil things to packets.

Server -- Linux -- Same Subnet -- No Jitter
Old Computer -- Windows XP -- Same Subnet -- No Jitter
New Computer -- Windows XP -- Same Subnet -- Jitter out the Wazoo

Hmmm... I switch network ports with no change. I turn NIC card offloading on and off with no change. I lower the speed -- no change.

Suddenly I notice negative ping times on my computer. This is getting really weird. I knew it -- I have discovered how to make a time warp.

A quick search of 'negative pings' turns up this page:

Negative Ping Time - Luke Jackson

And sure enough he and I have the same processor. I install the AMD patch and voila -- no more ping jitter.

Computers are just too damned quirky.