igb broken? Unexplained weirdness with intel 82576 nics on a supermicro board.

[Ian FREISLICH]

joe wrote:
> On 05/08/2010 06:55 AM, Ian FREISLICH wrote:
> > joe wrote:
> >>       I have just tried your suggeston and it has no effect for me ;(
> >
> > Do you have another brand of NIC that you can try?  At least that
> > will isolate whether it's igb(4) or something else.
> 
> I will grab a new nic today and try...my options are limited though. 
> Here are the nics i can get my hands on
> 
> TP-LINK TL-TG3468, 10/100/1000Mbps PCIe Adapter (supported by fbsd?)

Based on the RTL8168B chip.  Should be supported by the re(4) driver.

> Intel (EXPI9301CT) Gigabit CT Desktop Adapter (yet another intel nic)

i82574L chip.  Should be supported by the em(4) driver.  I have had
good performance in the past with this driver and less than
satisfactory performance with the igb(4) driver.

That may not be your problem though.  Before you go out and buy,
have a look at the amount of interrupt time your slow machine spends
in 'top' or 'systat -vm'.  systat will also show the interrupt rate
for each driver, perhaps it's not doing interrupt moderation properly.
This will manifest as more than about a 1000 per second.  There are
loader tunables for the driver to increase the number of transfer
descriptors and to tune interrupt moderation.

You could try running trafshow (port) on the interface while
performing the transfer.  Perhaps promiscuous mode will turn off
some hardware feature that will improve things.  It may however
break hardware vlanning as it does on my 82575GB 4 port igb card.

Ian

--
Ian Freislich