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From: jonathan <johnscpg@googlemail.com>
Newsgroups: comp.lang.ada
Subject: Re: Ada Shootout program for K-Nucleotide (patches)
Date: Wed, 19 Aug 2009 12:22:02 -0700 (PDT)
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Quick report on the the multitasking version
of knucleotide, using an 8-core machine.

Running on a single core, (single worker task)
it takes 35 seconds (same as the task-free version
of knucleotide):

   Split_Work: array (1 .. 1) of Writer;

begin
   Split_Work(1).Set (Nucleotide_Length => 1);
   Split_Work(1).Set (Nucleotide_Length => 2);
   Split_Work(1).Set (Fragments.Length (Fragment_3), Fragment_3);
   Split_Work(1).Set (Fragments.Length (Fragment_4), Fragment_4);
   Split_Work(1).Set (Fragments.Length (Fragment_6), Fragment_6);
   Split_Work(1).Set (Fragments.Length (Fragment_12), Fragment_12);
   Split_Work(1).Set (Fragments.Length (Fragment_18), Fragment_18);

time ./knucleotide < fasta250.dat

real    0m35.267s
user    0m35.002s
sys     0m0.252s


Using 4 worker tasks, it takes 13.6 seconds (best result). But
come to think of it, if there is a fifth env task aiding execution,
then it may benefit from the fact that there are 8 cores on
my machine.  Tasking overhead is negligible.

   Split_Work: array (1 .. 4) of Writer;

begin
   Split_Work(3).Set (Fragments.Length (Fragment_12), Fragment_12);
   Split_Work(4).Set (Fragments.Length (Fragment_18), Fragment_18);
   Split_Work(1).Set (Nucleotide_Length => 1);
   Split_Work(2).Set (Nucleotide_Length => 2);
   Split_Work(1).Set (Fragments.Length (Fragment_3), Fragment_3);
   Split_Work(2).Set (Fragments.Length (Fragment_4), Fragment_4);
   Split_Work(1).Set (Fragments.Length (Fragment_6), Fragment_6);

time ./knucleotide < fasta250.dat

real    0m13.653s
user    0m35.478s
sys     0m0.288s


I have put my version of the 1-core knucleotide.adb at

   http://web.am.qub.ac.uk/users/j.parker/

in directory bench_depository.
I made an attempt to prettify the text to my tastes, then lost
steam.  It seems to be identical to the new multicore version.
The only difference is a marginally stronger hash_function, which
I played with out of curiosity.  (Concluded that overhead
from calculating H is essentially insignificant, certainly
compared to benefit of avoiding collisions.)

  for J in 1 .. Key.Last loop
     H := Character'Pos (Key.Data (J)) +
           H * 2**3 + H * 2**6 + H * 2**11 - H;
  end loop;
  return Hash_Type'Base (H mod Uns_32(Hash_Type'Last + 1));

The older one, which may be better on more
general (ie longer) strings, and it is cetainly safer:
someone verified that it works in general.


Jonathan