[Haskell-cafe] Performance of functional priority queues

[Matt Morrow]

On 12/23/09, Jon Harrop <jon at ffconsultancy.com> wrote:
> And your results above indicate that the fastest imperative heap is over 3x
> faster than the fastest functional heap?

It's saying that

  (1) Using an imprecise an inefficient-relative-to-a-accurate-GC-that-doesn't-
        have-to-assume-the-entire-memory-space-is-live-then-find-what's-dead
        is a recipe for inefficiency.
  (2) And (1) even more so when you're comparing it to the same language with
       manual memory management and zero GC overhead.

  (from here on out I disregard the C numbers (i like C, too))

  (3) So now, it's saying that (given this sample, yada yada) among languages
        where this comparison is possible (i.e. the mutable version
still has the GC running)
        the functional version is on average 1.8 times slower.

          ghci> ((126/70) + (290/150) + (1895/1123)) / 3
          1.8069258929454834

Matt

> On Tuesday 16 June 2009 23:50:45 Richard O'Keefe wrote:
>> I've now done some benchmarks myself in C, Java, and Smalltalk,
>> comparing "imperative" versions of leftist heaps with "functional" ones.
>> For what it's worth, on a 2.16GHz Intel Core 2 Duo Mac, the
>> coefficient in front of the log(n) part was
>>
>>                  C       Java    ST(A)   ST(B)
>> "Imperative"    40       70     150     1123
>> "Functional"   240      126     290     1895
>>
>> where ST(A) was a native-code Smalltalk and ST(B) a byte-code one.
>> The C/Functional case used the Boehm collector, untuned.
>> Times are in nanoseconds.  Values of n ranged from 2 to 100; the
>> correspondent was saying that small sizes were important.
>>
>> It seems that a factor of 2 for *this* problem is credible;
>> a factor of 10 is not.