Messages in this thread | | | Date | Wed, 2 Jun 1999 18:07:07 -0500 (CDT) | From | Oliver Xymoron <> | Subject | Re: zero-copy TCP fileserving |
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On Wed, 2 Jun 1999, Bjorn Wesen wrote:
> Speaking of shortcuts, what is the status of some sort of direct > page -> skb TCP sending ? > > What I mean is, when tcp does a sendmsg, it shouldn't need to copy the > actual data into the skbuf, but merely the headers, and remember a ptr to > the data area (which would have to be locked down until the fragment is > acked or the connection breaks, of course). Then the network driver could > (if it supports s/g DMA) send the headers + data directly from memory.
This simple zero-copy isn't really a win on most PC hardware as it takes about the same amount of time to do a checksum as it does to do a checksum and copy.
A more powerful scheme is being investigated by sct and a couple others. A related scheme worked out on FreeBSD and presented at a recent Usenix could cache checksums, for example.
-- "Love the dolphins," she advised him. "Write by W.A.S.T.E.."
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