Negative latency

meanderful.blogspot.com

7 pointsFtuuky2 comments

The numbers seem completely improbable. No one would trade on 15-second-old market data: "And perhaps this means 15,625,200 us of latency as measured at t MD 3 at the telco gear interface to the building’s fibre (generously)."

Secondly, you cannot reason about network latency based solely on bandwidth. This matter is more complicated and depends among other things on the type of the medium and signal modulation techniques. One can have low-bandwidth ultra low-latency link.

Also, most players in the game use kernel bypass so processing packets is a matter of nano-, not microseconds.

Otherwise, a very interesting read.

Yep, that was a rather bad typo. 15,825 us. No excuse, except I shouldn't post in the wee hours of the morning ;-) I'm not really arguing about measured latency but you have to apply a best-case cost as you cannot measure certain parts of hidden infrastructure than you can't touch. You do know 1000 bits on a 1Mbps line will take "at least" 1000 microseconds.

Even your kernel bypass driver on a SolarFlare still takes at least 40us on 4000 bits from a 100Mbps KRX UDP feed in those older days, as that is simply the best case time on the wire.

True on nanoseconds being the common measure today.

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