Multiport NICs - VLAN and Polling Support?

[Danial Thom]

--- Kurt Jaeger <lists at complx.LF.net> wrote:

> Hi!
> 
> > polling is almost never a performance
> advantage
> > for ethernet, as virtually all modern
> controllers
> > have some sort of interrupt moderation
> built-in.
> 
> We had the case on fbsd 5.4p7 with SMP where
> bge drivers produced
> much slower throughput if we did not use
> polling. We measured using
> ttcp and the difference was from 2-3Mbyte/sec
> to 11 Mbyte/sec.
> 
> Yes, it used more CPU, but for that increase in
> throughput, it
> was worth the expense.
> 
> So it looks a bit strange from my part of the
> world to.
> 
> -- 
> MfG/Best regards, Kurt Jaeger                  

You have some other forces are work there
obviously. There is no possible way that polling
would yield a 5 fold increase in performance.
You're still using the same cpu to do the tasks.
11MG/s is such a small number of packets that it
wouldn't generate enough interrrupts to make much
difference to a modern processor. Thats what
happens when you use benchmarks. Benchmarks are
BS.

Probably one of the many "features" that FreeBSD
5.x offers. It likely it has more to do with
FreeBSD 5s handling of interrupts in an SMP
environment than anything having to do with
polling.

DT

Danial


	
		
__________________________________ 
Yahoo! Mail - PC Magazine Editors' Choice 2005 
http://mail.yahoo.com