Messages in this thread | | | Date | Sun, 3 Sep 2000 12:08:08 +0200 | From | "Andi Kleen" <> | Subject | Re: zero-copy TCP |
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On Sun, Sep 03, 2000 at 10:18:50AM +0200, Ingo Molnar wrote: > > On 2 Sep 2000, Jes Sorensen wrote: > > > You can't DMA directly from a file cache page unless you have a > > network card that does scatter/gather DMA and surprise surprise, > > 80-90% of the cards on the market don't support this. [...] > > exactly. The TUX patch solves this by copying 'multi-fragment skbs' into a > temporary single-fragment skb, if the card doesnt support scatter-gather, > 64-bit DMA. This way the copying is delayed as much as possible, to the > point where we queue the packet to the network device.
I did the same for fragment RX some months ago (simple fragment lists that were copy-checksummed to user space). Overall it is probably better to use a kiovec, because that can be more easily used in nfsd and sendfile.
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