[gambit-list] Speed improvement of lib/digest.scm
lucier at math.purdue.edu
Wed Nov 18 13:05:41 EST 2009
On Thu, 2009-02-19 at 17:07 -0500, Marc Feeley wrote:
> On 19-Feb-09, at 4:57 PM, Marc Feeley wrote:
> > On my 2GHz Mac Book Pro:
> > For MD5: 0.06 seconds per MB.
> > For SHA-1: 0.13 seconds per MB.
> > That's still about 3 times slower than the "md5" utility on my
> > machine, but still not too bad for bit-bashing code entirely written
> > in Scheme.
> By the way this slowdown is due to the 16-bit algorithms which are
> used to perform the computations without overflowing the fixnums. The
> C version probably does 32-bit operations, which is at least a factor
> of 2 faster, and probably more when shifts are involved.
And on my 64-bit Core 2 duo running ubuntu it's quite a bit worse:
> (time (digest#digest-file "Fedora-12-ppc-DVD.iso" 'sha-1))
(time (digest#digest-file "Fedora-12-ppc-DVD.iso" 'sha-1))
245908 ms real time
244740 ms cpu time (241710 user, 3030 system)
12312 bytes allocated
8 minor faults
no major faults
heine:~/Desktop/Fedora-12-ppc-DVD> time sha1sum Fedora-12-ppc-DVD.iso
18.390u 1.670s 2:03.13 16.2% 0+0k 1160296+0io 0pf+0w
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