> They still go over the various techniques used, their consequences, etc., so the processor chosen as an example is unimportant.
They also include various techniques not used anymore, without mentioning that’s the case. I did a search for “branch predictor static forward not taken site:.edu” and found many documents which discuss that particular BTFN technique. In modern CPUs the predictor works before fetch or decode.
> university courses don't cover that
Here’s a link to one: https://course.ece.cmu.edu/~ece740/f15/lib/exe/fetch.php?med... According to the first slide, the document was written in fall 2015. It has dedicated slides discussing particular implementations of branch predictors in Pentium Pro, Alpha 21264, Pentium M, and Pentium 4.
The processors being covered were released between 1995 and 2003. At the time that course was written, people were already programming Skylake and Excavator, and Zen 1 was just around the corner.
I’m not saying the professor failed to deliver. Quite the opposite, information about old CPUs is better than pure theory without any practically useful stuff. Still, I’m pretty sure they would be happy to included slides about contemporary CPUs, if only that information was public.
> They also include various techniques not used anymore, without mentioning that’s the case.
Definitely. Sometimes it's for comparative reasons, and sometimes it's easier to understand the newer technique in the context of the older one.
> discussing particular implementations of branch predictors in Pentium Pro, Alpha 21264, Pentium M, and Pentium 4.
Yeah, but the course is still not the optimization guide you wanted. The slides pick & choose features from each branch predictor to make the point the professor wanted to make and present the idea he wanted to. It's not really useful for optimizing code for that particular processor, it's useful for understanding how branch predictors work in general.
> I’m pretty sure they would be happy to included slides about contemporary CPUs, if only that information was public.
Only if they served as a good example for some concept, or helped make a point that the professor wanted to make. There's no point in changing the examples to a newer processor if the old one is a cleaner implementation of the concept being discussed (and older examples tend to be simpler and therefore cleaner). The point isn't to supply information about specific processors, it's to teach the techniques used in branch predictors.
P.S. See those 3 slides about a "Perceptron Branch Predictor"? Based on a paper from 2001? I'm betting AMD's "neural network" is really just something like that...
They also include various techniques not used anymore, without mentioning that’s the case. I did a search for “branch predictor static forward not taken site:.edu” and found many documents which discuss that particular BTFN technique. In modern CPUs the predictor works before fetch or decode.
> university courses don't cover that
Here’s a link to one: https://course.ece.cmu.edu/~ece740/f15/lib/exe/fetch.php?med... According to the first slide, the document was written in fall 2015. It has dedicated slides discussing particular implementations of branch predictors in Pentium Pro, Alpha 21264, Pentium M, and Pentium 4.
The processors being covered were released between 1995 and 2003. At the time that course was written, people were already programming Skylake and Excavator, and Zen 1 was just around the corner.
I’m not saying the professor failed to deliver. Quite the opposite, information about old CPUs is better than pure theory without any practically useful stuff. Still, I’m pretty sure they would be happy to included slides about contemporary CPUs, if only that information was public.