WIth respect, I think this shows nothing :-)
On Oct 21, 2013, at 2:35 PM, Sam Tobin-Hochstadt <sa...@cs.indiana.edu> wrote: > On Mon, Oct 21, 2013 at 12:47 PM, Matthias Felleisen > <matth...@ccs.neu.edu> wrote: >> >> In general, it is a mistaken assumption however that even in a >> 'managed' language -- such as Java or Racket -- mutation is still >> faster than de/allocation of short-lived data structures. If you >> choose to go with 'managed' language, you need to adapt your >> programming style to the new context. > > Sadly, this assumption is often right for Racket today, even though we > have a pretty good allocator. Here's a simple benchmark: > https://gist.github.com/samth/7088570 > > This just passes multiple arguments between two functions in three > ways: with a cons, with multiple values, and by mutating an mcons > (plus a direct version with two local variables). In all cases, it's > as fast as I can make it, using unsafe operations where appropriate. > > Here are some representative timings: > > [samth@huor:~/sw/plt/racket/collects/racket/match (master) plt] r > /tmp/bench.rkt > 'direct > cpu time: 40 real time: 44 gc time: 0 > 'cons > cpu time: 72 real time: 73 gc time: 12 > 'values > cpu time: 192 real time: 191 gc time: 0 > 'mcons > cpu time: 48 real time: 51 gc time: 0 > > Direct is always fastest, multiple values are very slow, and cons is > always slower than mcons. Even if we ignore GC time, the functional > version is still always slower. > > Sam ____________________ Racket Users list: http://lists.racket-lang.org/users
