small tun(4) improvement

[Gleb Smirnoff]

On Thu, Oct 14, 2004 at 08:01:46PM +0200, Andre Oppermann wrote:
A> >   any objections about commiting this improvement to tun(4)?
A> > In my ng_device I have a similar function ngdwrite(), which was
A> > cut-n-pasted from tunwrite(). And my tests with a patched ng_device have
A> > shown 30% speedup on large writes. I don't think it will help tun(4)
A> > to be a much faster, since tunwrite() isn't a bottleneck, but I think
A> > it is worth considering. The patch was tested on a production PPPoE access
A> > concentrator (RELENG_4 however).
A> 
A> Could you check tap(4) as well?  You can do the same optimization there
A> as well (IIRC).

Yes, you are right.

We are going to have triple cut'n'paste: if_tun.c, ng_device.c, if_tap.c.
What about m_uiocopy()? The question is where can we put this function?

P.S. We already have md_get_uio() in libmchain. But it doesn't do exactly
same thing. And libmchain does not support Big Endians, so we probably
don't want to make tun and tap depend on libmchain.

P.P.S. BTW, ng_eiface+ng_device is going to supersede tap(4), same way as
ng_iface+ng_device is going to supersede tun(4).  :)

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