lkml.org 
[lkml]   [1999]   [May]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [patch] checksum P6 asm buffer overflow fix + 686 improvements


On Mon, 24 May 1999, Andrea Arcangeli wrote:

> I also improved a bit the asm (mainly the csum_copy that wasn't
> unrolling enough according to the new numbers).

Unrolling more eats more instruction cache for incredibly low gain, I
don't think it's a good idea except maybe for dedicated routers. As for
the other changes, such as changing testl %esi,%esi to clc, that hurts the
current code (we spent a LOT of time putting the right instructions in
there, and got some very non-obvious results a lot of times, due to
alignment issues and other PPro weirdness I guess).

I also noticed that you removed the code that handles 2-byte aligned
areas, I don't think that's a very good idea, all the adcl instructions
will probably slow down a lot if they don't operate on aligned data.

If there is interesting in improving the checksum codes, I can try to dig
out my old test program which let you benchmark with various "real-life"
packet sizes with both warm and cold i-cache and d-cache.

- Finn Arne


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:51    [W:1.144 / U:0.032 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site