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Re: TSO + e1000

To: anton@xxxxxxxxx (Anton Blanchard)
Subject: Re: TSO + e1000
From: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Date: Mon, 06 Dec 2004 12:26:26 +1100
Cc: netdev@xxxxxxxxxxx, ganesh.venkatesan@xxxxxxxxx, jesse.brandeburg@xxxxxxxxx, john.ronciak@xxxxxxxxx
In-reply-to: <20041205232226.GA5757@xxxxxxxxxxxxxxxxxxxxxxxxxx>
Organization: Core
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Anton Blanchard <anton@xxxxxxxxx> wrote:
> 
> 1. tcpdump doesnt report local TSO packets, it simply prints bad-len. I
> think this is because the e1000 driver is zeroing out the IP header
> length in e1000_tso:
> 
>        skb->nh.iph->tot_len = 0;
> 
> Does the card require this for TSO to operate? Ive worked around it in 
> tcpdump for the time being.

This is a bug in e1000.  Even if it is required it isn't allowed to
modify a cloned packet.  It'll need to copy it so that other clone
users aren't affected.
 
> Now if we do a single direction test it takes forever for TSO to kick
> in. At the moment Im not sure why this is happening, tcp_current_mss
> seems to grow correctly in both cases. Is there somewhere else we are
> capping TSO packets?

What call does your application use to do the sending?

Cheers,
-- 
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Email: Herbert Xu ~{PmV>HI~} <herbert@xxxxxxxxxxxxxxxxxxx>
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