Assembly string functions in i386 libc

[Sean C. Farley]

While looking at increasing the speed of strlen(), I noticed that on
i386 platforms (PIII, P4 and Athlon XP) the performance is abysmal in
libc compared to the version I was writing.  After more testing, I found
it was only the assembly version that is really slow.  The C version is
fairly quick.  Is there a need to continue to use the assembly versions
of string functions on i386?  Does it mainly help slower systems such as
those with i386 or i486 CPU's?

I have the results from my P4 (Id = 0xf24 Stepping = 4) system and the
test program here[1].  strlen.tar.bz2 is the archive of it for anyone's
testing.  In the strlen/results subdirectory, there are the results for
strings of increasing lengths.

I would appreciate it if anyone could see if strlen and strlen2 perform
any better on an amd64.  Although the current C version of strlen() in
7-CURRENT is faster than mine for smaller values, they perform better
for larger strings.

I doubt people would want either of my versions in CURRENT just before
the freeze :), but it would be nice to use the C version we do have
instead of the assembly version.  I cannot speak about the other string
functions as I have not tested them.

Sean
   1. http://www.farley.org/freebsd/tmp/
-- 
scf at FreeBSD.org