Optimizing Code Performance When Branch Prediction Works Against You

A couple of days ago I was thinking about what you can do when the branch predictor is effectively working against you, and thus pessimizing your program instead of optimizing it.

Let's work with something relatively simple & concrete: consider that we want to write some kind of financial system (maybe a trading system) and all of our transaction requests arrive at a certain function before being either (a) sent out to some authoritative server, or (b) abandoned.

The vast majority of our transaction requests end up being abandoned at the last step.

We care A LO