TCP Segmentation Offload (TSO) in 2.4?

TCP Segmentation Offload (TSO) in 2.4?

[Roy Sigurd Karlsbakk]

hi

I've got some servers doing quite a lot of network traffic, and after reading 
the article about TSO on kernel traffic 
(http://www.kerneltrap.org/node.php?id=397), I wonder ... will this be 
backported to 2.4? is it hard?

thanks

roy
-- 
Roy Sigurd Karlsbakk, Datavaktmester
ProntoTV AS - http://www.pronto.tv/
Tel: +47 9801 3356

Computers are like air conditioners.
They stop working when you open Windows.

Re: TCP Segmentation Offload (TSO) in 2.4?

[David S. Miller]

   From: Roy Sigurd Karlsbakk <roy@karlsbakk.net>
   Date: Thu, 17 Oct 2002 11:05:14 +0200

   I've got some servers doing quite a lot of network traffic, and after reading 
   the article about TSO on kernel traffic 
   (http://www.kerneltrap.org/node.php?id=397), I wonder ... will this be 
   backported to 2.4? is it hard?

It isn't hard, but two issues:

1) You'll only get this with e1000 cards, and there were some
   performance regression noted by some testers at IBM with
   TSO enabled.

2) There are semantic issues still unresolved in the generic
   TCP implementation parts, such as how to deal with the
   fact that the way to get the most out of TSO is to
   ignore the congestion window at connection startup.  We
   can only really make such a violation when talking to a
   host on the local network etc. etc.

   A 2.4.x backport is illadvisable until this is resolved.

RE: TCP Segmentation Offload (TSO) in 2.4?

[Feldman, Scott]

> It isn't hard, but two issues:
> 
> 1) You'll only get this with e1000 cards, and there were some
>    performance regression noted by some testers at IBM with
>    TSO enabled.

Was this posted to the list?  I remember Troy's results showing positive
results with TSO over SPECWeb.  

-scott

Re: TCP Segmentation Offload (TSO) in 2.4?

[David S. Miller]

   From: "Feldman, Scott" <scott.feldman@intel.com>
   Date: Thu, 17 Oct 2002 16:35:18 -0700

   > 1) You'll only get this with e1000 cards, and there were some
   >    performance regression noted by some testers at IBM with
   >    TSO enabled.
   
   Was this posted to the list?  I remember Troy's results showing positive
   results with TSO over SPECWeb.  
   
Mala Anand (manand@us.ibm.com) has continually been disabling TSO in
2.5.x performance tests, at least this is how it has appeared to me.

Please, you two have a dialogue together and sort this out :-)