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From: Jeff Garzik <jgarzik@pobox.com>
To: Joakim Tjernlund <Joakim.Tjernlund@lumentis.se>
Cc: linux-kernel@vger.kernel.org
Subject: Re: NETIF_F_SG question
Date: Sat, 01 Feb 2003 12:40:20 -0500	[thread overview]
Message-ID: <3E3C0684.4010806@pobox.com> (raw)
In-Reply-To: <004701c2ca03$cb467460$020120b0@jockeXP>

Joakim Tjernlund wrote:
> I am thinking of implementing harware scatter/gatter support( NETIF_F_SG) in my 
> ethernet driver. The network device cannot do HW checksuming.
> 
> Will the IP stack make use of the SG support and will there be any significant performance
> improvement?


No; you need HW checksumming for NETIF_F_SG to be useful.

If HW checksumming is not available, scatter-gather is useless, because 
the net stack must always make a pass over the data to checksum it. 
Since it must do that, it can linearize the skb at the same time, 
eliminating the need for SG.

	Jeff




  reply	other threads:[~2003-02-01 17:33 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-02-01 15:08 NETIF_F_SG question Joakim Tjernlund
2003-02-01 17:40 ` Jeff Garzik [this message]
2003-02-01 18:42   ` Joakim Tjernlund
2003-02-01 19:16     ` romieu
2003-02-01 22:16       ` Joakim Tjernlund
2003-02-02  1:39   ` Joakim Tjernlund
2003-02-03 21:18     ` Ion Badulescu
2003-02-03 22:22       ` Joakim Tjernlund
2003-02-03 22:34         ` Ion Badulescu
2003-02-03 22:44           ` Joakim Tjernlund

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