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Re: on the wire behaviour of TSO on/off is supposed to be the same yes?

To: Rick Jones <rick.jones2@xxxxxx>
Subject: Re: on the wire behaviour of TSO on/off is supposed to be the same yes?
From: Jon Mason <jdmason@xxxxxxxxxx>
Date: Fri, 21 Jan 2005 13:58:53 -0600
Cc: netdev@xxxxxxxxxxx
In-reply-to: <41F1516D.5010101@xxxxxx>
Organization: IBM
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The benefit of TSO is not throughput, but CPU utilization.  Throughput 
increase is usually a side effect because of better PCI DMA behavior (eg. 
large PCI transfers are better).  Are you seeing a CPU utilization decrease?

On Friday 21 January 2005 01:01 pm, Rick Jones wrote:
> Is it indeed supposed to be the case that the on the wire behaviour of TCP 
> with 
> TSO on/off is supposed to be the same?  I'm seeing some cases (netperf 
> TCP_STREAM 2.6.10 sending to HP-UX 11.23) where the throughput differences 
> are 
>  >= 10 MB/s on an e1000 card (TSO being slower).  I've got lots of netperf 
> and 
> tcpdump but thought I'd ask first before dumping it onto the list.  Actually, 
> i'll probably have to put it up on the net somewhere since it is O(200MB) in 
> total (although I have a smaller point example).
> 
> sincerely,
> 
> rick jones
> 
> 
> 

-- 
Jon Mason
jdmason@xxxxxxxxxx

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