Re: [PATCH 2/2] [e1000 VLAN] Disable vlan hw accel when promiscuous mode

[David Miller <davem@davemloft.net>]

From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Tue, 13 Nov 2007 20:03:28 +0800

> On Tue, Nov 13, 2007 at 03:36:11AM -0800, David Miller wrote:
> >
> > The performance implications can be pretty severe however.
> > I wish we could address this somehow.
> 
> Or perhaps we should just teach everyone to always run tcpdump
> with -p, like me :)

:-)

> Of course this would still have a negative impact on those who
> have to be in promiscuous mode all the time (heh) due to multiple
> unicast MAC addresses and such.  However, we should able to
> communicate that fact to the driver and the driver can then elect
> to not disable VLAN acceleration unless we really want to be in
> promiscuous mode.

We already do with the code Patrick added a while ago so
that drivers can support multiple MAC addresses in hardware.

Now just to get the virtualization technologies and all the
drivers using it properly.

> In other words we can make it so that nobody is in promiscuous
> mode and therefore have to disable VLAN acceleration *unless*
> they really want to be in that state.  In which case it would
> imply that they wish to see everything and therefore we should
> disable VLAN acceleration.

This is too complicated, we have multiple unicast MAC support
in the driver API already, let's simply use it.