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Re: Q: (ab)using zerocopy for drivers with alignment contraints

To: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Subject: Re: Q: (ab)using zerocopy for drivers with alignment contraints
From: Andi Kleen <ak@xxxxxx>
Date: Wed, 13 Jun 2001 03:19:29 +0200
Cc: netdev@xxxxxxxxxxx
In-reply-to: <3B238B31.38F6D3ED@colorfullife.com>; from manfred@colorfullife.com on Sun, Jun 10, 2001 at 04:58:57PM +0200
References: <3B238B31.38F6D3ED@colorfullife.com>
Sender: owner-netdev@xxxxxxxxxxx
On Sun, Jun 10, 2001 at 04:58:57PM +0200, Manfred Spraul wrote:
> Several cheap busmaster nics only accept tx buffers that are 32-bit
> aligned.
> 
> Currently they memcpy into transfer buffers. What about replacing that
> memcpy with csum_copy_partial_nocheck and enabling NETIF_F_{SG,HW_CSUM}? 

[...] I'll probably not give you much gain in 2.4 anymore. Both TCP and UDP
do csum and copy to user in most fast path cases.

-Andi

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