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

joe joe at hostedcontent.com
Sat May 8 17:18:11 UTC 2010

On 05/08/2010 11:17 AM, Ian FREISLICH wrote:
> 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

I bought those two cards anyways, im in a rush to figure out this 
problem. That being said i am still encountering the exact same problem 
regardless on which network card i am running. I am at a complete loss. 
I am about to try a raid card to see if the problem might lay within the 
onboard sata ports. I did pull the server and brought it home so that i 
can test more things quicker.

I am going to try using a raid card instead of the onboard sata ports 
and see if i still encounter the same problem. I would love any 
suggestions you may have on where to go from here to figure out where 
the problem might be.


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