Messages in this thread | | | Date | Mon, 3 Feb 2003 16:18:41 -0500 | From | Ion Badulescu <> | Subject | Re: NETIF_F_SG question |
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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.
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...
> (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.
Ion [starfire driver maintainer]
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