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Date: Mon, 09 Sep 2002 17:58:21 +0900 (JST)
Message-Id: <20020909.175821.108746773.taka@valinux.co.jp>
To: davem@redhat.com
Cc: "Feldman, Scott" <scott.feldman@intel.com>, nfs@lists.sourceforge.net,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH] zerocopy NFS for 2.5.33
From: Hirokazu Takahashi <taka@valinux.co.jp>
In-Reply-To: <20020909.001902.28439948.davem@redhat.com>
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	<20020909.001902.28439948.davem@redhat.com>
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Hi,

As far as I know e1000 has a feature that it can split a jumbo UDP frame
into some IP fragments.

>    From: Hirokazu Takahashi <taka@valinux.co.jp>
>    Date: Mon, 09 Sep 2002 16:11:23 +0900 (JST)
> 
>    Using TSO code is commented out at this moment as TSO for UDP isn't
>    implemented yet. I'm waiting for it so that we would remove "#ifdef NotYet"
>    to send jumbo UDP frames without any fragmentation and any checksumming.
>    Then I hope we will get great performance.
>    
> Actually, device interface for what could be used is there, see
> NETIF_F_FRAGLIST.  No devices set this and IP never makes use of it
> yet though :-)
> 
> Acenic and Tigon3 will be able to do this, probably e1000 has this
> feature as well.
> 
> But it does not work how you imagine.  One passes already fragmented
> list of packets to card, and it can checksum the packet if you tell it
> which descriptor is first of fragmented frame and which is last.
> 
> It does not do the fragmentation of UDP frames for you, only
> checksumming of UDP portion.  No card does what you mention.
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