time to execute instructions

[juliomacedo]

Where can I find information about time taken (in cpu cycles) to execute each machine instruction so we can choose which ones to use in a specific situation?

I'm sure I saw this anywhere, I thought it was in Intel manuals but I can't find this information...

[zooba]

Doesn't exist anymore, AFAIK, because there are too many variables.

Just test your algorithm and change as much as you can until you find the best. But keep in mind, it probably won't be the best on the next computer :wink

[hutch--]

zooba is right here, the magic word is "pipeline" and the action is "scheduling" instructions in the best possible order to get the most through without stalling the pipeline(s).

Think of a pipeline as a production line. No single instruction goes through all that fast but the average output is a lot more than 1 at a time.

It would be good value if you downloaded the complete set of Intel manuals and put some time into the optimisation manual. It will tell you most of the tricks and the rest you get through testing and timing on multiple machines.

[MazeGen]

Take a look at http://www.agner.org/assem/pentopt.pdf