On Tue, 2012-08-21 at 00:37 +0200, Ludovic Courtès wrote: > I wrote: > > > Note that (ice-9 format) is an order of magnitude slower, though: > > > > scheme@(guile-user)> (f 4000) > > clock utime stime cutime cstime gctime > > 260.14 258.94 0.51 0.00 0.00 63.19 > > $1 = #f > > > > Admittedly, this should be fixed, but that’s another story... > > A bit of profiling shows this: > > --8<---------------cut here---------------start------------->8--- > scheme@(guile-user)> ,pr (with-output-to-port (%make-void-port "w") (lambda > () (let loop ((i 40000)) (or (zero? i) (begin (format #t "~a ~a~%" 'foo 'bar) > (loop (1- i))))))) > % cumulative self > time seconds seconds name > 15.70 2.13 0.34 format > 10.74 1.39 0.23 tilde-dispatch > 10.74 0.96 0.23 call-with-output-string > 7.44 0.20 0.16 #<procedure b042600 at ice-9/r4rs.scm:236:3 (p)> > [...]
hi Ludo! I recall something about tilde-displatch since you mentioned it. A guy discussed the efficiency of format with me years ago, I talked with Andy, but then I forgot it: --------------------code------------------- scheme@(guile-user)> ,profile (let lp ((i 10000)) (if (> i 0) (begin (format #f "0x~2'0x, 0x~2'0x, 0x~2'0x" i i i) (lp (1- i))))) % cumulative self time seconds seconds name 22.58 0.56 0.23 tilde-dispatch 12.90 1.00 0.13 format 12.90 0.13 0.13 number->string 8.06 0.13 0.08 format:out-char 4.84 0.80 0.05 format:format-work --------------------end------------------- In this case, we tried "0x~2'0x" and it's so slow that we can't bare it. i=10000 is fast, but we need (* 600 80000) And we found that "tilde-dispatch" cost too much. Is there any possible to optimize it? > Sample count: 121 > Total time: 2.183744831 seconds (0.77482795 seconds in GC) > --8<---------------cut here---------------end--------------->8--- > > Procedure #4 is ‘with-output-to-string’, so we can easily improve that > by using ‘call-with-output-string’ directly instead: > > --8<---------------cut here---------------start------------->8--- > scheme@(guile-user)> ,pr (with-output-to-port (%make-void-port "w") (lambda > () (let loop ((i 40000)) (or (zero? i) (begin (format #t "~a ~a~%" 'foo 'bar) > (loop (1- i))))))) > % cumulative self > time seconds seconds name > 17.39 0.56 0.28 call-with-output-string > 14.13 0.24 0.23 #<procedure 11e5a1a0 at > /home/ludo/src/guile/module/ice-9/format.scm:782:46 (p)> > 13.04 1.58 0.21 format > 9.78 1.27 0.16 format:format-work > [...] > Sample count: 92 > Total time: 1.597127172 seconds (0.513423265 seconds in GC) > --8<---------------cut here---------------end--------------->8--- > > Commit 6c9220064d987deee813cfd933d50353d14d4c0f. > > To be continued... > > Ludo’.
