Re: NETIF_F_SG question

From: Jeff Garzik (jgarzik@pobox.com)
Date: Sat Feb 01 2003 - 12:40:20 EST


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

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/



This archive was generated by hypermail 2b29 : Fri Feb 07 2003 - 22:00:08 EST