Subject: Re: freebsd em driver
To: None <>
From: Thor Lancelot Simon <>
List: tech-net
Date: 06/17/2002 16:52:59
On Mon, Jun 17, 2002 at 08:49:36PM +0200, Frank van der Linden wrote:
> Could you perhaps include actual performance figures (and of course
> how you obtained them)? I'm always very interested in performance
> comparisons, but plain statements like "it's on par with" or
> "FreeBSD is faster" are hard to verify, or indeed makes it
> hard to fix if there is a problem there.
> On Mon, Jun 17, 2002 at 11:31:50AM -0700, Jonathan Stone wrote:
> > Myself, I just want a driver that runs at (or near) wire speed on some
> > of the current-generation (under US$100 and trending down) boards.
> Wire speed is Hard to obtain still. Numbers vary greatly, especially
> with gig-e over copper. If you're doing 50-60 MB/sec over IP, userspace
> to userspace, and using normal framesizes, you're doing alright.
> That's still only half the wire speed. If you want to go higher,
> you'll need jumbo frames, and a faster/wider PCI bus.


At least two vendors manage to get 90MB/sec or more using Tigon-II cards
with modified firmware, even with slow CPUs (e.g. MIPS R10K at 170MHz)
and wide-but-slow (64/33) PCI buses.  This is with *standard* size frames.

The comments at the head of the FreeBSD BCM570x and Intel Gig-E drivers
appear to state that they can deliver similar performance on a modern
machine.  But the experience of SGI and others with old hardware and slow
CPUs does seem to imply that even with small frames, it can be done.

 Thor Lancelot Simon	                            
   But as he knew no bad language, he had called him all the names of common
 objects that he could think of, and had screamed: "You lamp!  You towel!  You
 plate!" and so on.              --Sigmund Freud