On Sun 18 Jun 06, 12:06 AM, Norm Matloff <[EMAIL PROTECTED]> said: > Pete Salzman asked about optimizing a loop in terms of execution speed, > by having the loop index go from high value to low instead of vice > versa. Some discussion ensued in terms of what machine instructions a > compiler could take advantage of in this manner. > > One point that you might consider, Pete, is that these considerations > are kind of nickel-and-dime in comparison to things like memory > hierarchy issue. There is much better payoff potential in writing code > in such a way as to minimize cache misses, which cause major time > penalties, and page faults, which cause catastrophic time penalties.
Yeah, I know. My company hired me for algorithmic optimizations --- my knowledge of devising a set of algorithms to accomplish a given task (e.g., solving dense matrices, choosing a particular Monte Carlo for a given problem). I guess my attitude towards this was more along the lines of "while I'm in the neighborhood, why don't I stop by and say hello". It certainly wouldn't be prudent to re-implement code to use nickel and dime optimization, but while thoughts in my neurons travel down my CNS and translate into my fingers tapping on keys, I might as well tap on keys in such a way that the nickel and dime optimizations appear on vim's terminal. The price of admission is free, so I might as well. OK. I took that nutty metaphor as far as it can go. Hope it made sense. > There is even a book on this, I believe in the Intel Press series. Definitely sounds like a book I should pick up. I'll Google for it! Thanks, Pete _______________________________________________ vox-tech mailing list [email protected] http://lists.lugod.org/mailman/listinfo/vox-tech
