Re: is CONFIG_PACKET_MMAP always a win?

From: Jamie Lokier (lk@tantalophile.demon.co.uk)
Date: Fri Feb 22 2002 - 14:04:31 EST


Alan Cox wrote:
> > > Overhead: kernel does a full memcpy of the packet body to get it
> > > into the ring buffer, and my program does another to get it out.
> >
> > I had a look at this about a year ago, and it seems there is no method
> > provided to read the packets without copying them, if you need them in
> > user space.
>
> You can process them in the ring buffer. If you can't keep up then you
> are screwed any way you look at it 8)

That still doesn't avoid copying: af_packet copies the whole packet (if
you want the whole packet) from the original skbuff to the ring buffer.

-- Jamie
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