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SubjectRe: zero-copy TCP
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>>>>> "Jeff" == Jeff V Merkey <jmerkey@timpanogas.com> writes:

Jeff> Jes Sorensen wrote:
>> 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.

Jeff> I guess this is a correct statement, but Linux and everyone else
Jeff> has the same limittion. Here, I'll refrase. Zero copies
Jeff> irregardless of the driver model. Intel had an ethernet card
Jeff> that did years back. So Alan's statements are also wrong since
Jeff> he says "one DMA" not applicable to cards with a shared memory
Jeff> window.

I know cards exist that can do the job, however it has first become
widely available with the Gigabit cards. I only know of a few 100baseT
cards that can do it such as the Adaptec Starfire and the 3C905B
(though I am not sure what it provides is sufficient). As for the
Intel EEPro100 series than it's probably true they can do it, but we
were never allowed to get information on the magic to enable it.

We are working on zero copy and it makes sense for some stuff, but
it's not as simple an issue as a lot of people make it out to be.

Jes
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