[netdrivers] latest on gige cards and performance?

Donald Becker becker@scyld.com
Wed Aug 27 19:42:05 2003

On Wed, 27 Aug 2003, Jeremy Hansen wrote:

> I'm in the process of planning a gigE network and I'd like to get the 
> latest on performance tuning for gigE copper and what cards to look at for 
> maximum performance.  If there is a gigE FAQ, please point me to it.

No good FAQ that I know of.  It's much more difficult to get information
about the internal design of GbE adapters than it was a few years ago.

> Right now what I have available to play with is a Cisco 6509 with a 48port 
> 10/100/1000 copper blade and a few e1000's.

The exact model of the e1000 is important.  The rapid churn of PCI ID
numbers for the e1000 cards reflects the changes in the internal
structure and firmware of the chips.  The e1000 cards are much smarter
about looking at the payload of packets and basing interrupt decisions
on the contents.  This is good for latency and typical performance, but
makes it difficult to do micro-benchmarks.

>  I'd like to benchmark the 
> different speeds I'm getting while playing with MTU's on these machines 
> but netperf doesn't seem to like it when I set to MTU to 9000.  Ttcp seems 
> to do the same.  Our goal is to see somewhere around 500M/s of raw TCP 
> between our servers and workstations.

Getting jumbo frames to work is tricky.  Jumbo frames are not part of
the standard, for good technical reasons.

Have you configured the switch to match the exact size configured on the
Linux machine?

Donald Becker				becker@scyld.com
Scyld Computing Corporation		http://www.scyld.com
914 Bay Ridge Road, Suite 220		Scyld Beowulf cluster system
Annapolis MD 21403			410-990-9993