Messages in this thread | | | Subject | Re: zero-copy TCP | From | Jes Sorensen <> | Date | 03 Sep 2000 00:22:02 +0200 |
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>>>>> "Jeff" == Jeff V Merkey <jmerkey@timpanogas.com> writes:
Jeff> **ALL** Netware network drivers support a scatter/gather Jeff> proramming interface, whether the hardware does or not. In Jeff> NetWare, the drivers get passed a fragment list in what's called Jeff> an ECB (Event Control Block). It's the drivers responsiblity to Jeff> assemble the fragment lists. We did it this way to support Jeff> scatter/gather cards and non-scatter gather cards in one Jeff> interface. Those drivers that do not support scatter gather DMA Jeff> operations copy to a local buffer to assemble the packet. Those Jeff> with a shared memory window copy data from the fragment list Jeff> into this window until a complete IEEE frame gets completed Jeff> (since it will get copied anyway), then hit the register bits to Jeff> initiate a send of the data.
You just told us earlier in the thread that NetWare does direct zero copy DMA but thats only half the story obviously. Up until the era of Gigabit Ethernet cards there were almost no PCI cards available that would do scatter/gather so obviously netware wasn't doing zero copy either.
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