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DateSat, 01 Feb 2003 12:40:20 -0500
FromJeff Garzik <>
SubjectRe: NETIF_F_SG question
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



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