Re: FreeBSD's new zero-copy networking

From: Alan Cox (alan@lxorguk.ukuu.org.uk)
Date: Mon Sep 18 2000 - 10:45:17 EST


> Yup. That's true. Like it's also nonintuitive sometimes that PIO can even
> beat, in some cases, DMA (some graphics fifo devices, e.g.).

It can be true for networking devices in some cases too. Ive been playing at
putting K7 prefetch instructions in the ethernet drivers and netif_rx so
that the packet header is back in cache after the DMA invalidated it when
fetching the packet

> > I think Jes was getting this in Linux TCP/IP without zero copy.
> What was the CPU utilization?

I dont know. I suspect pretty high.

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