Skip to contentSkip to conversation

Athlon fast_copy_page revisited

DISCUSSION Gordon Sadler 1 participant 1 message Jun 2, 2001 1 message not in the archive

lore
Share & tools
lore

A message that is not in the archive (sent off-list or not yet received): [email protected]

Gordon Sadler

author
#1 lore raw

[This message has also been posted.]
On Wed, 30 May 2001 18:09:35 GMT, Jimmie Mayfield
<[email protected]> wrote:
<SNIP explanation>

Quoted 24 lines

Arjan's original code is at: http://www.fenrus.demon.nl/athlon.c
My modifications are at: http://sackheads.org/~mayfield/jrm_athlon.c

Example test runs:

copy_page() tests

copy_page function 'warm up run'         took 21350 cycles per page
copy_page function '2.4 non MMX'         took 27706 cycles per page
copy_page function '2.4 MMX fallback'    took 28600 cycles per page
copy_page function '2.4 MMX version'     took 21370 cycles per page
copy_page function 'faster_copy'         took 13119 cycles per page
copy_page function 'even_faster'         took 14767 cycles per page
copy_page function 'jrm_copy_page_8nop'  took 12774 cycles per page

copy_page function 'jrm_copy_page_10nop' took 12746 cycles per page
copy_page function 'jrm_copy_page_12nop' took 12740 cycles per page

copy_page() tests

copy_page function 'warm up run'         took 22499 cycles per page
copy_page function '2.4 non MMX'         took 27769 cycles per page
copy_page function '2.4 MMX fallback'    took 27696 cycles per page
copy_page function '2.4 MMX version'     took 22666 cycles per page
copy_page function 'faster_copy'         took 13058 cycles per page
copy_page function 'even_faster'         took 13169 cycles per page
copy_page function 'jrm_copy_page_8nop'  took 12691 cycles per page
Quoted 6 lines

copy_page function 'jrm_copy_page_10nop' took 12750 cycles per page
copy_page function 'jrm_copy_page_12nop' took 14786 cycles per page

The values obviously fluctuate depending on system activity but the jrm_* routines were faster in 13 out of 15 trials.

I have a Duron 800 socket A on an Epox 8KTA3.
Has anyone noticed fluctuations with these tests.. such as jrm_athlon1:
...
copy_page function 'faster_copy' took 9869 cycles per page
copy_page function 'even_faster' took 9822 cycles per page
...
jrm_athlon2:
...
copy_page function 'faster_copy' took 9939 cycles per page
copy_page function 'even_faster' took 17728 cycles per page
...
jrm_athlon3:
...
copy_page function 'faster_copy' took 17711 cycles per page
copy_page function 'even_faster' took 9843 cycles per page
...

I see these with gcc 2.95.4(Debian unstable) and a local build of gcc-3.0 from CVS last night.

Almost as though some stall and/or caching is corrupting the results.

Signature · 1 line
Gordon Sadler