Re: digest algorithm performance

[Jim Meyering]

address@hidden wrote:
...
> OK, I'll have a look. FreeBSD seems to be faster again,
> (don't compare these results to the previous mail):

[I've just noticed you used `sha1' below.
 Is that a shell alias or function?
 The program from coreutils is called sha1sum. ]

> $time sha1 < 15MBfile
> 51e673b839d5bee3293fa2f1dd58c69face9770a
...
> $time openssl sha1 < 15MBfile
> 51e673b839d5bee3293fa2f1dd58c69face9770a
...

FYI, here are a few more data points:

  On an AMD-64 system, using a 700MB file on a tmpfs file system
  (and enough RAM so that no actual disk reads are performed),
  GNU md5sum is slightly faster than `openssl md5', e.g.:

    2.38s user 0.38s system 100% cpu 2.756 total  (gnu md5sum)
    vs.
    2.52s user 0.34s system 100% cpu 2.869 total

  However, `openssl sha1' is about 5% faster than GNU sha1sum:

    3.32s user 0.33s system 99% cpu 3.653 total   (openssl sha1)
    3.45s user 0.39s system 99% cpu 3.843 total   (gnu sha1sum)

The above are using the debian-sid (amd_64 alioth) binaries from
coreutils-5.2.1.  When I compile the latest (coreutils-cvs) with
gcc-4.0 -O3, I get slightly (2-3%) better sha1sum performance,
and a ~7% *decrease* in performance for md5sum.  I suspect that
with the right compiler options you can do much better.