On Wed, Jan 25, 2006 at 08:33:57PM +0100, Manuel Bouyer wrote:
> On Wed, Jan 25, 2006 at 08:01:47PM +0100, Pavel Cahyna wrote:
> > On Wed, Jan 25, 2006 at 07:50:57PM +0100, Manuel Bouyer wrote:
> > > On Wed, Jan 25, 2006 at 12:22:06PM +0100, Pavel Cahyna wrote:
> > > > the itended effect...
> > > > 
> > > > What is the purpose of hardware VLAN tagging, anyway? The performance
> > > > impact will be rather negative, because searching the VLAN tag in the
> > > > linear list of mbuf tags will be probably slower than simply prepending it
> > > > to the mbuf. It also seriously limits usability of tcpdump (tcpdump sees
> > > 
> > > I can tell you that it has a positive inpact on a Alpha DS20 with a
> > > gigabit interface; I get a 10% increase with tcpdump.
> > 
> > tcpdump?
> 
> Sorry, I meant ttcp

Do you have any explanation why does it help?

Could be HW tagging made conditional on some setting, like hardware
checksums (if the hardware allows turning them off)?

Pavel Cahyna