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

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:

quoted

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.