[ntp:questions] Recommendations for good NIC cards

Rick Jones rick.jones2 at hp.com
Mon Apr 19 18:31:09 UTC 2010

> > How do you configure it on Linux?
> http://freshmeat.net/projects/ethtool/

> ( never used it myself yet )

I've used it from time to time in my guise as "Mr. Netperf" - the
biggest issue I have with it is that you have to script it post-boot -
the linux folks eschew having module parameters for "things that can
be set via ethtool."  Also, the specifics of what you can/should
change can vary from NIC to NIC.

Where one can first see if the defaults are "bad" for interrupt
coalescing would be the output of a netperf TCP_RR test between two of
those NICs on a private network.  If the inverse of the transaction
rate is not "close to" (for a fairly liberal definition of close) the
service demand (CPU consumption) per transaction, likely as not
interrupt coalescing is taking place.

Or, you can simply try changing the coalescing and if the transaction
rate increases you know the default was bogus from a latency

I've seen that on a number of GbE NICs, and 10GbE NICs.  I have seen
good (IMO) default behaviour with the likes of the HP AD386A 10 GbE
NIC, which is based on a Chelsio T3C chip.  I think I've seen good
default behaviour on a couple other 10G NICs as well, but their names
escape me !-(

rick jones
The computing industry isn't as much a game of "Follow The Leader" as
it is one of "Ring Around the Rosy" or perhaps "Duck Duck Goose." 
                                                    - Rick Jones
these opinions are mine, all mine; HP might not want them anyway... :)
feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

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