Messages in this thread |  | | Date | Sun, 3 Sep 2000 19:21:50 +0200 (CEST) | From | Ingo Molnar <> | Subject | Re: zero-copy TCP |
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On Sun, 3 Sep 2000 almesber@lrc.di.epfl.ch wrote:
> If we go for a Linux-specific solution anyway, maybe one could add > another send{,to,msg} flag that makes send*(2)'s buffer access > non-atomic. That way, the kernel only needs to make sure the pages > don't disappear, but there's no need for expensive MMU games. > > Of course, this would give applications a way for generating packets > with an incorrect TCP/UDP checksum, [...]
i believe such zero-copy send should only be allowed for drivers which can guarantee correct checksums. (ie. cards which do Tx-checksums) The other drivers will still copy. I dont think this is a problem - the number of cards that can do scatter-gather DMA but cannot do TX-checksumming is rather low. (i only know about the Tulip.) All modern cards do TX-checksumming and scatter-gather DMA.
Ingo
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