On Sun, Jul 22, 2012 at 3:33 PM, Jon Zeppieri <zeppi...@gmail.com> wrote: > On Sun, Jul 22, 2012 at 4:15 PM, Robby Findler > <ro...@eecs.northwestern.edu> wrote: >> I don't have any good guesses as to which files trigger the problem, >> but you could time 'raco make' to try to hone in specific files. Run >> 'raco make' once to build all of a file's dependencies (or just have >> finished a raco setup run) and then delete compiled/file_rkt.zo if >> file.rkt is the file you want to time and run 'raco make' on it. > > Thanks. I'll give that a try. > >> >> But 7-15 seconds seems like it could easily just be because it takes a >> very small amount of time more per case expression and there are a lot >> of case expressions. > > Right -- and I'm hoping to eliminate, or at least to minimize, that > very small amount of time. > > However, it's possible that I was wrong about the cause of the bold > time difference. Today I updated my 'case-v3' branch with the changes > that have been committed to the plt master branch since the two > diverged, and I separately cloned the current plt master to a > different directory. (Previously, I had been using a tarball as the > control.) And I started running the build tests again. That's still > going on, but so far, the preliminary results are the opposite of the > ones from the other day. My 'case-v3' branch tends to build slightly > faster. > > Obviously, there are any number of things that can account for the > build time difference: background processes eating up CPU, physical > file location on disk, etc. If the numbers continue to come out as > they are now, I'll just conclude that the build time really isn't > significantly affected one way or the other. > >> >> Have you considered a hybrid approach where you first count the number >> of clauses and only use your new implementation when it is above some >> threshold? > > My implementation does something like that; it counts the number of > constants, rather than the number of clauses. That's what Clinger's > version does, too, and it's probably very slightly more expensive than > just counting the clauses, but I doubt the difference is noticeable. > The syntax-case clause looks like: > > [(_ v [(k ...) e1 e2 ...] ... [else x1 x2 ...]) > (if (< (length (syntax-e #'(k ... ...))) *sequential-threshold*) > (syntax/loc stx (let ([tmp v]) > (case/sequential tmp [(k ...) e1 e2 ...] > ... [else x1 x2 ...]))) > (syntax/loc stx (let ([tmp v]) > (case/dispatch tmp [(k ...) e1 e2 ...] > ... [else x1 x2 ...]))))] > > ... where case/sequential build an if-then-else tree.
Oh right. I probably subconsciously remembered that from reading the paper and from thence came my suggestion. If you're really trying to dot your i's and cross your t's, you could write a script that looks 'case' expressions, find the top 10 files in terms of expression size or expression count and time them using raco make. Robby _________________________ Racket Developers list: http://lists.racket-lang.org/dev
