Messages in this thread | | | From | "Joakim Tjernlund" <> | Subject | Re: NETIF_F_SG question | Date | Mon, 3 Feb 2003 23:44:00 +0100 |
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> On Mon, 3 Feb 2003, Joakim Tjernlund wrote: > > > > 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? > > Nope. You're looking at this the wrong way: the goal is not zero copy, but > zero data access by CPU. Once you realize that, it's clear that SG alone > is no good. > > This is not necessarily the only approach, but it is the current approach > in the Linux IPv4 stack. It's not worth the effort to re-engineer the code > in order to support the fast-disappearing hardware which supports SG but > not cksums.
Agreed. > > > zerocopy without requiring HW cksums only OR could for instance the forwarding > > procdure also benefit from SG without requiring HW cksums? > > The forwarding procedure is already dealing with linear buffers because > 99.99% of the network cards on the market receive packets into one linear > buffer. So again SG is useless for that.
I see, thanks for your patience with me.
Joakim > > Ion
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