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Re: [PATCH 2.6.12-rc4] IPv4/IPv6: UDP Large Send Offload feature

To: ravinandan.arakali@xxxxxxxxxxxx
Subject: Re: [PATCH 2.6.12-rc4] IPv4/IPv6: UDP Large Send Offload feature
From: Stephen Hemminger <shemminger@xxxxxxxx>
Date: Fri, 27 May 2005 08:57:13 -0700
Cc: davem@xxxxxxxxxxxxx, jgarzik@xxxxxxxxx, netdev@xxxxxxxxxxx, raghavendra.koushik@xxxxxxxxxxxx, ravinandan.arakali@xxxxxxxxxxxx, leonid.grossman@xxxxxxxxxxxx, ananda.raju@xxxxxxxxxxxx, rapuru.sriram@xxxxxxxxxxxx
In-reply-to: <20050526232006.60E6365005@linux.site>
Organization: Open Source Development Lab
References: <20050526232006.60E6365005@linux.site>
Sender: netdev-bounce@xxxxxxxxxxx
On Thu, 26 May 2005 16:20:06 -0700 (PDT)
ravinandan.arakali@xxxxxxxxxxxx wrote:

> Hi,
> Attached below is a kernel patch to provide UDP LSO(Large Send Offload) 
> feature.
> This is the UDP counterpart of TSO. Basically, an oversized packet
> (less than or equal to 65535) is handed to the NIC. The adapter then
> produces IP fragments in conformance with RFC791(IPv4) or RFC2460(IPv6).
> 
> Very much like TCP TSO, UDP LSO provides significant reduction in CPU 
> utilization, especially with 1500 MTU frames. For 10GbE traffic,
> these extra CPU cycles translate into significant throughput increase 
> on most server platforms.
> 
> Reasonable amount of testing has been done on the patch using Neterion's
> 10G Xframe-II adapter to ensure code stability.
> 
> Please review the patch.
> 
> Also, below is a "how-to" on changes required in network drivers to use
> the UDP LSO interface.

The only downside is that it might encourage continued use of NFS over UDP.
Perhaps we need a big fat warning in NFS that says:

*** Your using NFS over UDP, your data integrity is no longer guaranteed;
*** you have been warned.


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