Re: zero-copy TCP fileserving

Alan Cox (alan@lxorguk.ukuu.org.uk)
Fri, 4 Jun 1999 13:49:51 +0100 (BST)

> > As most (if not all) network drivers do load the entire frame onto the
> > card before beginning transmission, this is a possibility.
>
> Linus has pointed out that good cards fetch the data from memory as it
> is transmitted (is this true?) so I'll eat my words before everyone else
> does. :-)

Often it isnt true. They send one frame while fetching the next from
main memory. This avoids tons of crap packets caused by PCI bus latency
and the like but has almost identical performance under real I/O conditions

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