From: Ion Badulescu <ionut@cs.columbia.edu>
To: harish.vasudeva@amd.com
Cc: linux-kernel@vger.kernel.org
Subject: Re: Need some help with IP/TCP Checksum Offload
Date: Fri, 22 Feb 2002 19:00:53 -0500 [thread overview]
Message-ID: <200202230000.g1N00rw21538@buggy.badula.org> (raw)
In-Reply-To: <CB35231B9D59D311B18600508B0EDF2F04F280E6@caexmta9.amd.com>
On Fri, 22 Feb 2002 14:57:22 -0800, harish.vasudeva@amd.com wrote:
>
> I am trying to offload checksum calculation to my hardware. What i am doing in my driver (kernel 2.4.6) is :
>
> dev->features = NETIF_F_IP_CHECKSUM;
>
> Then, in my start_xmit( ) routine, i am parsing for the right headers & when i get the IP/TCP header, i print out the checksum & it is already the right checksum. When does the OS/Protocol offload this task? Am i missing something here?
I haven't looked at this in a long time, but at the time the checksum
offloading support was introduced, the IP stack needed both NETIF_F_SG
and NETIF_F_IP_CSUM in dev->features before it would start offloading.
The idea was that cksum support without scatter-gather support is useless,
because the csum gets calculated essentially for free while copying the data
to linearize the skbuf.
Ion
--
It is better to keep your mouth shut and be thought a fool,
than to open it and remove all doubt.
next prev parent reply other threads:[~2002-02-23 0:01 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-02-22 22:57 harish.vasudeva
2002-02-22 23:52 ` Benjamin LaHaise
2002-02-23 0:00 ` Ion Badulescu [this message]
2002-02-23 7:34 ` Andi Kleen
2002-02-24 17:48 ` Marek Zawadzki
2002-02-23 0:56 harish.vasudeva
2002-02-25 16:22 ` Ion Badulescu
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