Performance problem using Intel X520-DA2

Jack Vogel jfvogel at
Mon Jan 23 20:50:29 UTC 2012

There may be some interrupt handling changes coming, but at least for
the moment you need to increase the storm threshold, or set it to 0 to
disable it.


On Mon, Jan 23, 2012 at 12:20 PM, Marcin Markowski <mmarkowski at>wrote:

>  Hello,
> We use FreeBSD as sniffer (libpcap programs) and we experience
> performance problems when incoming traffic is greater than 7.5Gbps/s.
> If we check 'top' we see that first irq from network card is using
> 100% CPU. I've tested this on FreeBSD 8.2-RELEASE and 9.0-RELEASE
> (on 9.0 we can see also kernel thread named {ix0 que} using 100% CPU),
> and both systems behave the same. In logs we see also:
> interrupt storm detected on "irq268:"; throttling interrupt source
> Our server platform is Intel SR2600URBRP, 2x Xeon X5650, 6GB RAM and
> NIC Intel X520-DA2.
> I'm not sure if problem is with NIC or motherboard in SR2600URBRP,
> because everything is fine when we use other server configuration:
> Intel SR1630GP, 1x Xeon X3450, 8GB RAM, NIC X520-DA2
> My /boot/loader.conf:
> kern.ipc.nmbclusters=262144
> hw.ixgbe.rxd=2048
> hw.ixgbe.txd=2048
> hw.ixgbe.num_queues=16
> /etc/sysctl.conf
> hw.intr_storm_threshold=10000
> --
> Marcin Markowski
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