igb interrupt moderation

[Barney Cordoba]

--- On Sun, 1/3/10, Michael Tüxen <Michael.Tuexen at lurchi.franken.de> wrote:

> From: Michael Tüxen <Michael.Tuexen at lurchi.franken.de>
> Subject: Re: igb interrupt moderation
> To: "Mike Tancsa" <mike at sentex.net>
> Cc: "Barney Cordoba" <barney_cordoba at yahoo.com>, jfvogel at gmail.com, freebsd-net at freebsd.org
> Date: Sunday, January 3, 2010, 11:38 AM
> On Jan 3, 2010, at 5:23 PM, Mike
> Tancsa wrote:
> 
> > At 11:13 AM 1/3/2010, Michael Tüxen wrote:
> >> >
> >> > Just a separate datapoint about this driver,
> unless I apply
> >> >
> >> > http://people.freebsd.org/~yongari/igb/igb.buf.patch6
> >> >
> >> > the driver is not really usable for me in
> RELENG_8 on the dual port version of the card
> >> Could you elaborate on what you mean by "not
> really usable"?
> > 
> > 
> > Hi,
> >        Some link state issues
> (getting confused about what port is up), problems at high
> packet rates.  I dont have this card in production, but
> in my test environment it was much more stable on RELENG_8
> with the above patch in that I was not able to wedge the
> box.  pps rates were pretty ok on a low end i7 as
> well.
> Thanks for the information. I'll give it a try. I have a
> problem when I flood
> a system with SCTP INITs. The system under attack becomes
> completely unresponsive
> on the console. However, it continues to send INIT-ACKs
> back. After the last
> commit from Jack it recovers after the attack. Not yet sure
> what is going on.
> Using the em driver does not have the problem. However,
> when using the em
> driver only one core is fully used, when using the igb
> driver both cores are fully
> used. Unfortunately I do not have a more than dual core
> machine available for
> this testing...

Try em and lower the interrupt moderation to something like 500 (about
100 packets per int is good). The latency isn't going to be noticable and
you'll see your cpu burden reduced quite a bit. 

Are you using a single NIC on a server, or do you have a firewall or
bridge?

Barney