different branch prediction results in different processors

Question

I would like to ask some things on branch prediction. I am completely aware of what it is and how do they work or their different types. My question is this: How does the processor that i will use each predictor's performance? I mean if I use the same bencmark, same predictor but different processors, will I expect the same hit rate? I think yes, because it is just a model and is not affected by the type of processor but I would like to be sure about that.

Answer 1

Well, the answer is 'it depends'. A predictor model is just a model. You can't have any guarantee about how a particular processor implementation of such model will perform. Most probably the performance of the predictor also depends on factors not directly related to the benchmark, for example interrupt delivery or process scheduling.

Generally, I think you can expect each predictors to have consistent trends even in different physical processors, but I won't expect a numerically equal hit rate.