Messages in this thread | | | From | "Joakim Tjernlund" <> | Subject | Re: NETIF_F_SG question | Date | Mon, 3 Feb 2003 23:22:34 +0100 |
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> On Sun, 2 Feb 2003 02:39:41 +0100, Joakim Tjernlund <Joakim.Tjernlund@lumentis.se> wrote: > > > > I think HW checksumming and SG are independent. Either one of them should > > not require the other one in any context. > > They should be independent in general, but they aren't when the particular > case of TCP/IPv4 is concerned. > > > Zero copy sendfile() does not require HW checksum to do zero copy, right? > > Wrong... > > > If HW checksum is present, then you get some extra performance as a bonus. > > You get zerocopy, yes. :-) No HW cksum, no zerocopy.
OK, but it should be easy to remove HW cksum as a condition to do zerocopy?
> > Don't let this stop you, however. It's always possible that other networking > stacks will eventually make use of SG while not requiring HW TCP/UDP cksums. > None of them do right now, but...
zerocopy without requiring HW cksums only OR could for instance the forwarding procdure also benefit from SG without requiring HW cksums?
> > > (hmm, one could make SG mandatory and the devices that don't support it can > > implement it in their driver. Just an idea) > > Not really, that way lies driver madness. The less complexity in the driver, > the better.
Just a wild idea, forget it. You are right
Joakim > > Ion > [starfire driver maintainer] - 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/
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